Internet

 

What is Internet?

Internet is a global network that connects billions of computers across the world with each other and to the World Wide Web. It uses standard internet protocol suite (TCP/IP) to connect billions of computer users worldwide. It is set up by using cables such as optical fibers and other wireless and networking technologies. TCP/IP = Transmission Control Protocol/ Internet Protocol.

It is believed that the internet was developed by "Defense Advanced Projects Agency" (DARPA) department of the United States. And, it was first connected in 1969.

Network Vs Internet

Network : A computer network is a group of computers linked to each other that enables the computer to communicate with another computer and share their resources, data, and applications.

The different between Network and Internet:

BASIS FOR COMPARISON	NETWORK	INTERNET
Basic	Combination of two or more computer systems.	Interconnection of several networks.
Coverage	Limited geographical area	Large geographical area

History of the Internet:

We know the the internet was developed by "Defense Advanced Projects Agency" (DARPA) department of the United States. The TCP/IP model defines how devices should transmit data between them and enables communication over networks and large distances.

The TCP/IP, open networking protocol suite, was adopted by the ARPANet in 1983, and the National Science Foundation Network (NSFN) developed the network to link university computer science departments across the US in 1985.

What is WWW?

The World Wide Web -- also known as the web, WWW or W3 -- refers to all the public websites or pages that users can access on their local computers and other devices through the internet. These pages and documents are interconnected by means of hyperlinks that users click on for information. Tim Berners-Lee, a British scientist, invented the World Wide Web (WWW) in 1989, while working at CERN.

Tim Berners-Lee was the man, who led the development of the World Wide Web, the defining of HTTP (HyperText Transfer Protocol), HTML (hypertext markup language) used to create web pages, and URLs (Universal Resource Locators). The development of WWW, HTTP, HTML and URLs took place between 1989 and 1991. Father of the Internet: Tim Berners-Lee. The browser was invented by Tim Berners-Lee.

What are the Applications of Internet?

Today is the era of Internet applications, today there is a specific application to do every work, using which you can do those tasks very easily. Today we will know in detail about the same applications of the Internet.

Communication : Communication is also one of the most used applications of the Internet because today it is very easy to talk through the Internet and today almost everyone is communicating with each other through the Internet. For example, you can talk to someone through chat, you can talk through voice call, you can talk through video call, etc.

Job Search : Through these internet job applications, you can find jobs for yourself sitting at home, these job portals have all kinds of jobs for all types of people, all you have to do is use these job applications and just send your resume. Today you can easily find jobs related to your skills through the internet and give a direct interview to HR.

Online Shopping : Today the whole world is doing online shopping through the internet, that too sitting at home and you can also shop online from home through the internet. Today there are many such applications on the Internet, through which you can buy anything online. Such as - Mobile, Tablet PC, Computers, Watch, Smart Watch, Television, Fan, Table Fan, LED Bulb, Glasses, Ring, Jewellers, Camera, Home Appliances, clothes, etc.

Stock Marketing : In the earlier times, no one knew about the stock market, what is the stock market, but today everyone knows about the stock market, what is the stock market and how to invest money in it. Today many people are earning a lot of money from the stock market, today people know which stock to invest in and when to sell which stock so that more money can be earned. Here we can buy or sell any stock without any broker and can also read the information of stock market moment by moment.

E-Banking : Today is the era of e-learning in the present time, e-learning means electronic learning which means you can now study from anywhere through e-learning. If you understand it in an easy language, now you can do your studies by staying in any corner of the world, now you do not need to go to any college or institute to study, You can study from online live class through e-learning sitting at home.

Computer Network Types:

A computer network can be categorized by their area coverage size. A computer network is mainly of four types:

LAN(Local Area Network)

PAN(Personal Area Network)

MAN(Metropolitan Area Network)

WAN(Wide Area Network)

LAN(Local Area Network)

1. Local Area Network is a group of computers connected to each other in a small area such as building, office.

2. LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable, etc.

3. It is less costly as it is built with inexpensive hardware such as hubs, network adapters, and ethernet cables.

4. The data is transferred at an extremely faster rate in Local Area Network.

5. Local Area Network provides higher security.

PAN(Personal Area Network)

1. Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters.

2. Personal Area Network is used for connecting the computer devices of personal use is known as Personal Area Network.

3. Thomas Zimmerman was the first research scientist to bring the idea of the Personal Area Network.

4. Personal Area Network covers an area of 30 feet.

5. Personal computer devices that are used to develop the personal area network are the laptop, mobile phones, media player and play stations.

There are two types of Personal Area Network:

1. Wireless Personal Area Network: Wireless Personal Area Network is developed by simply using wireless technologies such as WiFi, Bluetooth. It is a low range network.

2. Wired Personal Area Network: Wired Personal Area Network is created by using the USB and lan cable.

MAN(Metropolitan Area Network)

1. A metropolitan area network is a network that covers a larger geographic area by interconnecting a different LAN to form a larger network.

2. Government agencies use MAN to connect to the citizens and private industries.

3. In MAN, various LANs are connected to each other through a telephone exchange line.

4. The most widely used protocols in MAN are RS-232, Frame Relay, ATM, ISDN, OC-3, ADSL, etc.

5. It has a higher range than Local Area Network(LAN).

Uses Of Metropolitan Area Network:

1. MAN is used in communication between the banks in a city.

2. It can be used in an Airline Reservation.

3. It can be used in a college within a city.

4. It can also be used for communication in the military.

WAN(Wide Area Network)

1. A Wide Area Network is a network that extends over a large geographical area such as states or countries.

2. A Wide Area Network is quite bigger network than the LAN.

3. A Wide Area Network is not limited to a single location, but it spans over a large geographical area through a telephone line, fibre optic cable or satellite links.

4. The internet is one of the biggest WAN in the world.

5. A Wide Area Network is widely used in the field of Business, government, and education.

What is a network topology?

Topology defines the structure of the network of how all the components are interconnected to each other. There are two types of topology: physical and logical topology.

Types of Network Topology:

Physical topology is the geometric representation of all the nodes in a network. There are six types of network topology which are Bus Topology, Ring Topology, Tree Topology, Star Topology, Mesh Topology, and Hybrid Topology.

1. Bus Topology

1. The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone cable.

2. Each node is either connected to the backbone cable by drop cable or directly connected to the backbone cable.

3. When a node wants to send a message over the network, it puts a message over the network. All the stations available in the network will receive the message whether it has been addressed or not.

4. The bus topology is mainly used in 802.3 (ethernet) and 802.4 standard networks.

5. The configuration of a bus topology is quite simpler as compared to other topologies.

6. The backbone cable is considered as a "single lane" through which the message is broadcast to all the stations.

7. The most common access method of the bus topologies is CSMA (Carrier Sense Multiple Access).

CSMA: It is a media access control used to control the data flow so that data integrity is maintained, i.e., the packets do not get lost. There are two alternative ways of handling the problems that occur when two nodes send the messages simultaneously.

CSMA CD: CSMA CD (Collision detection) is an access method used to detect the collision. Once the collision is detected, the sender will stop transmitting the data. Therefore, it works on "recovery after the collision".

CSMA CA: CSMA CA (Collision Avoidance) is an access method used to avoid the collision by checking whether the transmission media is busy or not. If busy, then the sender waits until the media becomes idle. This technique effectively reduces the possibility of the collision. It does not work on "recovery after the collision".

Advantages of Bus topology:

1. Here, Nodes are directly connected to the cable without passing through a hub. Therefore, the initial cost of installation is low.

2. Coaxial or twisted pair cables are mainly used in bus-based networks that support upto 10 Mbps.

3. Bus topology is a familiar technology as the installation and troubleshooting techniques are well known, and hardware components are easily available.

4. A failure in one node will not have any effect on other nodes.

Disadvantages of Bus topology:

1. A bus topology is quite simpler, but still it requires a lot of cabling.

2. It requires specialized test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.

3. If two nodes send the messages simultaneously, then the signals of both the nodes collide with each other.

4. Adding new devices to the network would slow down the network.

2. Ring Topology:

1. Ring topology is like a bus topology, but with connected ends.

2. The node that receives the message from the previous computer will retransmit to the next node.

3. The data flows in one direction, i.e., it is unidirectional.

4. It has no terminated ends, i.e., each node is connected to other node and having no termination point.

5. The data in a ring topology flow in a clockwise direction.

Working of Token passing : (Token: It is a frame that circulates around the network.)

1. A token moves around the network, and it is passed from computer to computer until it reaches the destination.

2. The sender modifies the token by putting the address along with the data.

3. The data is passed from one device to another device until the destination address matches. Once the token received by the destination device, then it sends the acknowledgment to the sender.

4. In a ring topology, a token is used as a carrier.

Advantages of Ring Topology

1. The data transmission is high-speed.

2. The possibility of collision is minimum in this type of topology.

3. Cheap to install.

Disadvantages of Ring Topology

1. The failure of a single node in the network can cause the entire network to fail.

2. Troubleshooting is difficult in this topology.

3. The addition of stations in between or the removal of stations can disturb the whole topology.

3. Star Topology

1. Star topology is an arrangement of the network in which every node is connected to the central hub, switch or a central computer.

2. The central computer is known as a server, and the peripheral devices attached to the server are known as clients.

3. Coaxial cable or RJ-45 cables are used to connect the computers.

4. Hubs or Switches are mainly used as connection devices in a physical star topology.

5. Star topology is the most popular topology in network implementation.

Advantages of Star Topology

1. If N devices are connected to each other in a star topology, then the number of cables required to connect them is N. So, it is easy to set up.

2. It is high-performing as no data collisions can occur.

3. Robust in nature.

4. Easy fault detection because the link are often easily identified.

5. No disruptions to the network when connecting or removing devices.

Disadvantages of Star Topology

1. If the concentrator (hub) on which the whole topology relies fails, the whole system will crash down.

2. More expensive than linear bus topology due to the value of the connecting devices (network switches).

3. Hub requires more resources and regular maintenance because it’s the central system of star .

4. Extra hardware is required (hubs or switches) which adds to cost.

4. Tree topology

1. Tree topology combines the characteristics of bus topology and star topology.

2. A tree topology is a type of structure in which all the computers are connected with each other in hierarchical fashion.

3. The top-most node in tree topology is known as a root node, and all other nodes are the descendants of the root node.

4. There is only one path exists between two nodes for the data transmission. Thus, it forms a parent-child hierarchy.

Advantages of Tree Topology :

1. The other nodes in a network are not affected if one of their nodes gets damaged or does not work.

2. Tree topology provides easy maintenance and easy fault identification can be done.

3. Tree Topology is reliable.

4. It can support a large number of nodes

Disadvantages of Tree Topology

1. If any fault occurs in the node, then it becomes difficult to troubleshoot the problem.

2. A tree topology mainly relies on main bus cable and failure in main bus cable will damage the overall network.

3. Devices required for broadband transmission are very costly.

4. If new devices are added, then it becomes difficult to reconfigure.

5) Mesh topology

1. There are multiple paths from one computer to another computer.

2. It does not contain the switch, hub or any central computer which acts as a central point of communication.

3. The Internet is an example of the mesh topology.

4. Mesh topology is mainly used for WAN implementations where communication failures are a critical concern.

5. Mesh topology is mainly used for wireless networks.

Mesh topology can be formed by using the formula:

Number of cables = (n*(n-1))/2;

Where n is the number of nodes that represents the network.

Advantages of Mesh Topology :

1. Failure during a single device won’t break the network.

2. There is no traffic problem as there is a dedicated point to point links for every computer.

3. Fault identification is straightforward.

4. It provides high privacy and security.

5. This topology has robust features to beat any situation.

Disadvantages of Mesh Topology :

1. Installation is extremely difficult in the mesh.

2. Maintenance needs are challenging with a mesh.

3. If the network is not monitored carefully, then the communication link failure goes undetected.

4. Data must go through multiple nodes to reach its destination, this can result in slower network speeds.

6) Hybrid Topology

The combination of various different topologies is known as Hybrid topology or we can say it is the combination of two or more different topologies.

For example, in a college we have so many departments, let us say one department uses ring topology and another department uses Star topology, connecting these two topologies which results in Hybrid Topology.

It inherits the advantages and disadvantages of other topologies also.

Advantages of Hybrid Topology

1. It is effective and flexible.

2. Troubleshooting is easy.

3. Error detecting is reliable.

4. It is scalable because the size can be increased easily.

Disadvantages Hybrid Topology

1. Designing is difficult or complex.

2. It is costly. Due to the infrastructure cost is very high as a hybrid network requires a lot of cabling, network devices, etc.

Website Address and URL

A web address, or a Uniform Resource Locator (URL), is a unique reference that directs you to a specific page, file or photo on the internet. Without a web address, users cannot access a webpage.

Computer scientist Tim Berners-Lee developed the concept in 1994 to make the internet more accessible. He wanted to make the internet as user-friendly as possible, so he invented the web address to act as the standard access point for each individual webpage.

Components of a web address

Every web address follows the same format. Let’s use this page’s URL as an example to explore the individual components:

Example:

https://www.wix.com/encyclopedia/web-address/

Scheme: According to IBM, the scheme “identifies the protocol to be used to access the resource on the Internet.” The two most common schemes are http and https. This page uses https, meaning it has a secure sockets layer (SSL) certificate.

Example: https://www.wix.com/encyclopedia/web-address/

Domain name: A domain name is the website name correlating with its internet protocol (IP) address. The domain name indicates which connecting server the internet must use to locate the webpage. It also acts as the website’s primary name.

Example: https://www.wix.com/encyclopedia/web-address/

Domain extension: Also referred to as a top-level domain, a domain extension is the letters that follow the domain name. In our case, the domain extension is .com—the most common extension. The domain extension helps servers understand how to translate the web address into an IP address. Other common domain extensions include: .edu, .org, .gov and .net.

Example: https://www.wix.com/encyclopedia/web-address/

Path: The path follows the domain extension. This information specifies which webpage of the primary website the user wants to visit.

Example: https://www.wix.com/encyclopedia/web-address/

Subdomain: If you want to divide your website to improve navigation, you can create a subdomain—an addition to your web address that precedes the domain name. This page does not sit under a subdomain. However, if the encyclopedia was a subdomain, it might look like this:

Example: https://www.encyclopedia.wix.com/web-address/

Introduction to IP Address

IP stands for "Internet Protocol," which is the set of rules governing the format of data sent via the internet or local network. In essence, IP addresses are the identifier that allows information to be sent between devices on a network: they contain location information and make devices accessible for communication.

An IP address is a string of numbers separated by periods. IP addresses are expressed as a set of four numbers — an example address might be 192.158.1.38. Each number in the set can range from 0 to 255. So, the full IP addressing range goes from 0.0.0.0 to 255.255.255.255.

IP addresses are not random. They are mathematically produced and allocated by the Internet Assigned Numbers Authority (IANA), a division of the Internet Corporation for Assigned Names and Numbers (ICANN). ICANN is a non-profit organization that was established in the United States in 1998 to help maintain the security of the internet and allow it to be usable by all. Each time anyone registers a domain on the internet, they go through a domain name registrar, who pays a small fee to ICANN to register the domain.

What Is an Internet Service Provider (ISP)?

The term “internet service provider (ISP)” refers to a company that provides access to the internet to both personal and business customers. ISPs make it possible for their customers to surf the web, shop online, conduct business, and connect with family and friends.

ISPs make it possible for customers to access the internet while also providing additional services such as email, domain registration and web hosting. ISPs may also provide different internet connection types, such as cable and fiber.

How do ISPs work?

ISPs are connected to one or more high-speed internet lines. Larger ISPs have their own high-speed leased lines, so they are less dependent on telecommunications services and can provide better service to their customers.

ISPs also keep thousands of servers in data centers -- the number of servers depends on their internet service area. These large data centers manage all customer traffic. Multiple ISPs are also connected to large backbone routing centers.

What are the role of ISP?

1) An internet service provider’s main responsibility is to provide internet access to the companies, families, and individuals that subscribe to their service. This means that they are responsible for ensuring that the transfer of our data through the internet is instant and safely.

2)Depending on the price, an ISP provides subscribers with a certain bandwidth amount and internet speed. Internet service providers can also offer phone and cable television services.

3) An ISP should protect its subscribers from cyber threats and warn them if they are at risk.

What is the Internet Protocol (IP)?

The Internet Protocol (IP) is a protocol, or set of rules, for routing and addressing packets of data so that they can travel across networks and arrive at the correct destination.

Data traversing the Internet is divided into smaller pieces, called packets. IP information is attached to each packet, and this information helps routers to send packets to the right place. Every device or domain that connects to the Internet is assigned an IP address, and as packets are directed to the IP address attached to them, data arrives where it is needed.

Once the packets arrive at their destination, they are handled differently depending on which transport protocol is used in combination with IP. The most common transport protocols are TCP and UDP.

Note : Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.

Each device connected to the Internet has a unique IP address which other machines use to find the device. DNS servers eliminate the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex newer alphanumeric IP addresses such as 2400:cb00:2048:1::c629:d7a2 (in IPv6).

What is an IP address? How does IP addressing work?

An IP address is a unique identifier assigned to a device or domain that connects to the Internet. Each IP address is a series of characters, such as '192.168.1.1'. Via DNS resolvers, which translate human-readable domain names into IP addresses, users are able to access websites without memorizing this complex series of characters. Each IP packet will contain both the IP address of the device or domain sending the packet and the IP address of the intended recipient.

Types of IP Address

1) IPv4 (Internet Protocol Version 4)

2) IPv6 (Internet Protocol Version 6)

IPv4 :

IPv4 address consists of two things that are the network address and the host address. It stands for Internet Protocol version four. It was introduced in 1981 by DARPA and was the first deployed version in 1982 for production on SATNET and on the ARPANET in January 1983.

IPv4 addresses are 32-bit integers that have to be expressed in Decimal Notation. It is represented by 4 numbers separated by dots in the range of 0-255, which have to be converted to 0 and 1, to be understood by Computers. For Example, An IPv4 Address can be written as 189.123.123.90.

IPv4 Address Format

IPv4 Address Format is a 32-bit Address that comprises binary digits separated by a dot (.).

IPv6 :

IPv6 is based on IPv4 and stands for Internet Protocol version 6. It was first introduced in December 1995 by(IETF) Internet Engineering Task Force. IP version 6 is the new version of Internet Protocol, which is way better than IP version 4 in terms of complexity and efficiency. IPv6 is written as a group of 8 hexadecimal numbers separated by colon (:). It can be written as 128 bits of 0s and 1s.

IPv6 Address Format :

IPv6 Address Format is a 128-bit IP Address, which is written in a group of 8 hexadecimal numbers separated by colon (:).

Types of Internet Protocol

1) TCP/IP(Transmission Control Protocol/ Internet Protocol):

TCP/IP specifies how data is exchanged over the internet by providing end-to-end communications that identify how it should be broken into packets, addressed, transmitted, routed and received at the destination. TCP/IP requires little central management and is designed to make networks reliable with the ability to recover automatically from the failure of any device on the network.

2) SMTP :

SMTP is used to set up communication rules between servers. The servers have a way of identifying themselves and announcing what kind of communication they are trying to perform. They also have a way of handling the errors such as incorrect email address. For example, if the recipient address is wrong, then receiving server reply with an error message of some kind. Simple Mail Transfer Protocol (SMTP).

3) UDP :

UDP is a part of the Internet Protocol suite, referred to as UDP/IP suite. It is an unreliable and connectionless protocol. So, there is no need to establish a connection prior to data transfer. The UDP helps to establish low-latency and loss-tolerating connections establish over the network.The UDP enables process to process communication. User Datagram Protocol (UDP).

4) FTP :

FTP stands for File transfer protocol. FTP is a standard internet protocol provided by TCP/IP used for transmitting the files from one host to another. It is mainly used for transferring the web page files from their creator to the computer that acts as a server for other computers on the internet. It is also used for downloading the files to computer from other servers.

5) Hyper Text Transfer Protocol (HTTP):

HTTP is a communication protocol. It defines mechanism for communication between browser and the web server. It is also called request and response protocol because the communication between browser and server takes place in request and response pairs.

6) PPP :

The PPP stands for Point-to-Point protocol. It is the most commonly used protocol for point-to-point access. It is a data link layer protocol that resides in the layer 2 of the OSI model.

* Defining the frame format of the data to be transmitted.

* It defines the link establishment process. If user establishes a link with a server, then "how this link establishes" is done by the PPP protocol.

* The authentication between the two devices, handshaking and how the password will be exchanged between two devices are decided by the PPP protocol.

Modes of Connecting Internet:

1) Hotspot:

A hotspot is a physical location where people can access the Internet, typically using Wi-Fi, via a wireless local area network (WLAN) with a router connected to an Internet service provider.

2)Wi-Fi:

Wifi is also known as Wireless Fidelity. Wi-Fi is a wireless networking technology that permits to connect wirelessly to a network or to other computer or mobile device. A circular radio frequency range is used to transmit data in Wi-Fi. WLAN stands for Wireless Local Area Network. IEEE 802.11 is the rule for communication. WiFi uses the Physical Data Link Layer (PDLL) to operate. IEEE (Institute of Electrical and Electronics Engineers).

3) LAN Cable :

A LAN cable is a conductor that connects devices in a Local Area Network (LAN) with a network connector. The network cable provides communication between several devices (computers, routers, switches,…). The term “LAN” is an overtake for Ethernet cable.

Note: The main RJ45 (Registered Jack-45) is typically used in Ethernets or connecting cable modems with Wi-Fi routers.

There are three main types of LAN cables:

1) Coaxial cable : A coaxial cable is an electrical cable with a copper conductor and an insulator shielding around it and a braided metal mesh that prevents signal interference and cross talk. Coaxial cable is also known as coax.

A Coaxial Cable is mostly used in cable TV. It is also in computer network. A coaxial cable can be used over a distance of about 1 km and can achieve a transfer rate of up to 100 MBPS.( Mega Byte Per Second)

2) Copper twisted pair :

Twisted pair is a physical media made up of a pair of cables twisted with each other. A twisted pair cable is cheap as compared to other transmission media. Installation of the twisted pair cable is easy, and it is a lightweight cable. The frequency range for twisted pair cable is from 0 to 3.5KHz.

A twisted pair consists of two insulated copper wires arranged in a regular spiral pattern. The degree of reduction in noise interference is determined by the number of turns per foot. Increasing the number of turns per foot decreases noise interference.

Types of Twisted Pair Cable:

1) Unshielded Twiested Pair Cable:

UTP is an unshielded twisted pair cable used in computer and telecommunications mediums. It is a pair of insulated copper wires twisted together to reduce noise generated by external interference. It is a wire with no additional shielding, like aluminium foil, to protect its data from the exterior.

2) STP (Shielded twisted pair):

A shielded twisted pair is a type of twisted pair cable that contains an extra wrapping foil or copper braid jacket to protect the cable from defects like cuts, losing bandwidth, noise, and signal to the interference. It is a cable that is usually used underground, and therefore it is costly than UTP. It supports the higher data transmission rates across the long distance.

3) Fiber Optic Cable:

A fiber optic cable can contain a varying number of these glass fibers -- from a few up to a couple hundred. Another glass layer, called cladding, surrounds the glass fiber core. The buffer tube layer protects the cladding, and a jacket layer acts as the final protective layer for the individual strand.

BroadBand :

Broadband is a wide bandwidth transmission that can transmit multiple signals and data over a very high-speed internet connection. According to the Federal Communications Commission, a broadband connection has a minimum of 25 Mbps download speed and 3 Mbps of upload speed. There are 4 types of broadband connections, namely- DSL (Digital Subscriber Line), Cable, Fibre Optics and Satellite.

What is USB Tethering?

When the mobile internet connection is shared with a connected computer or laptop using physical USB data cable then it is called USB Tethering. It gives a high-speed connection while sharing the internet between mobile devices and connected computer systems, it is because Wired connection is quite stronger than Wireless LAN connection.

What is MAC Address?

MAC address is the physical address, which uniquely identifies each device on a given network. To make communication between two networked devices, we need two addresses: IP address and MAC address. It is assigned to the NIC (Network Interface card) of each device that can be connected to the internet. It stands for Media Access Control, and also known as Physical address, hardware address, or BIA (Burned In Address). It is globally unique; it means two devices cannot have the same MAC address. It is represented in a hexadecimal format on each device, such as 00:0a:95:9d:67:16.

IMEI :

IMEI stands for “International Mobile Equipment Identity.” It’s a unique number for identifying a device on a mobile network. You can think of it as your phone’s social security number. It has 15 digits and is assigned to every GSM phone.( Global System for Mobile Communication)

This number comes in handy when your handset gets lost or stolen. No, it won’t magically bring the phone back to you, but you can make sure whoever found or stole it won’t be able to use it. Your carrier can deny listing a device based on its IMEI number and request other carriers to do the same. This means the phone won’t make/receive calls anymore or connect online via the cellular network, even with a new SIM card.

Some Important Notes:

* List of letter addressing systems are:

.com : Commercial Organizations

.org : Non-Profitable Organizations

.gov : Government Departments

.net : Networking Organizations

.co : Company

.edu : Educational Institutions

.info : information

* Some country code related letter addressing system:

.in : India

.us : United States

.ca : Canada

.np : Nepal

.pk : Pakistan

What is a Browser?

A browser is a software program that is used to explore, retrieve, and display the information available on the World Wide Web. This information may be in the form of pictures, web pages, videos, and other files that all are connected via hyperlinks and categorized with the help of URLs (Uniform Resource Identifiers). For example, you are viewing this page by using a browser.

History of Browser:

1) The WorldWideWeb was the first web browser. It was created by W3C Director Tim Berners-Lee in 1990. Later, it was renamed Nexus to avoid confusion caused by the actual World Wide Web.

2) Lynx browser in 1992. It was not able to display the graphical content.

3) The first graphical user interface browser was NCSA Mosaic. It was the first most popular browser in the world, which was introduced in 1993.

4) Netscape Navigator in 1994.

5) Microsoft introduced the Internet Explorer in 1995.

6) A project started on Opera in 1994. Later, it was publicly introduced in 1996.

7) Apple's Safari browser was introduced in 2003. It was specifically released for Macintosh computers.

8) In 2004, Mozilla introduced Firefox as Netscape Navigator.

9) In 2007, a browser Mobile Safari was released as Apple mobile web browser.

10) The popular browser Google Chrome was launched in 2008.

11) The fast-growing mobile-based browser Opera Mini was released in 2011.

12 )The Microsoft Edge browser was launched in 2015.

What is surfing?

On the World Wide Web, surfing means to move from one Web page to another. When surfing, the user typically visits pages based on what interests him/her at the moment.

What is Search Engine?

A search engine is a software program that helps people find the information they are looking for online using keywords. Search engines are able to return results quickly—even with millions of websites online—by scanning the Internet continuously and indexing every page they find.

List of Search Engines are:

1 ) Bing

2) Google

3) Baidu

4) Yahoo

5) Ask.com

6) Yandex

7) Youtube

8) Lycos

9) DuckduckGo

10) Brave Search