Internet

Internet is the connection of millions of computers spread all over the world. It is the world largest computer network. It is the network of networks.

It is a public network so it is not owned by a particular user organization or government. However, it is controlled by internet authority.
Internet is initiated by US army. It was used for their internal communication but later, it become popular and used all over the world.

Uses of internet

1. Online communication: – It is used for online communication.
2. It is helpful for online business through e-commerce.
3. It is helpful for video conference.
4. It is helpful for e-ticketing, online reservation.
5. It helps to find information about various things.
6. It is used for entertainment.
7. It is used for downloading the video files, music files.
8. It is used for online job.
9. Advertisement.

Some terms related with Internet are:

1. Browser:-
A browser is internet based application software used to access a webpage. It sends request to the web server and displays the received HTML files in proper format user interact with the internet by using browser.
e.g. Google Chrome, Internet Explorer, Mozilla Firefox, Opera, Netscape, Safari, etc.

2. Search engine:-
It is also internet based application software. It can be used to access the required information or webpage address from the internet. A search engine maintains the record of all the websites and their contents. When the user requests by providing the keywords, it provides a list of websites and their links from its database. Google.com is the most common search engine at present. Other search engine includes bing.com, yahoo.com, altavista.com, webcrawler.com, etc.

3. Messenger service:-
A messenger is also internet based application software. It is used for communication. Such as text chat, audio-video chat, conference call, transmitting data and files, offline messages, etc. Some of the common messengers used are MSM messenger, Yahoo messenger, Google talk, AOL, Skype, etc.

4. Webpage:-
It is the fundamental unit of web. It is used to provide text emails, audio, video to the users. Webpage is developed by using scripting and web based programming language. Webpage are of two types:

1. Static
2. Dynamic

A static webpage is developed by using HTML.
Dynamic webpage is developed by using programming language like PHP, ASP, C#, etc along with HTML.

5. Website:-
A website is a location used for storing webpage. User access the webpage by using the website address. For e.g. facebook.com, tyrocity.com, babal.host, etc.

6. Web server:-
Web server is a program required to host webpage so that it can be accessed through the internet. To host webpage, the computer should have web server running, dedicated internet connection and the computer should be running all the time. The common web servers used are IIS (Internet Information Service) and Apache (for Linux based system).

7. URL (Uniform resource locator):-
It is a complete website address which is used to specify domain name, website location, and the protocol used for communication. A complete URL is provided to access a web site.
e.g. https://tyrocity.com, http://www.google.com.np.

8. Domain name system (DNS)
A domain name system is the process of using domain name to access a computer or website such as hotmail.com is a domain name. Domain names are easier to remember and access compared to IP address. However, communication is done through IP address. An IP address is a numerical value such as 192.168.1.1. It is used to identify a particular computer on a network. Since, these IP addresses are difficult to remember, domain names are used in place of IP address. A DNS translates domain name into corresponding IP address. Domain names are classified on the basis of type of organization and the country wise.

Type of organization:-
.com
.org
.edu
.gov
.net
.mil
.biz
.tv

Country wise:-
.np
.in
.sl
.pk
.uk
.au

9. Protocol:-
A protocol is a rule or standard defined to be used by all the components. Network protocol can be defined as the rules used for communication between two or more devices.

Some of the common network protocols used are:-

• HTTP ( Hyper Text Transfer Protocol)
• FTP (File Transfer Protocol)
• HTTPS (Hyper Text Transfer Protocol Secured)
• SMTP (Simple Mail Transfer Protocol)
• POP (Post Office Protocol)
• IMAP (Internet Mail Access Protocol)
• IP (Internet Protocol)
• TCP (Transmission Control Protocol)
• UDP (User Datagram Protocol)
• VOIP (Voice Over Internet Protocol)

- HTTP:
It is used for the communication of hypertext document. Webpages are the example of hypertext document. It is developed by using HTML and contains hyperlink.

- FTP:
It is used for the transmission of files like document image, audio, video, software, games, etc.

- HTTPS:
It is used for the transmission of hypertext document by providing higher security. It is mainly used by banking sector, e-commerce, and other electronic payment system where higher security is required. It uses encryption and decryption technique to provide security.

- SMTP, POP & IMAP:
These protocols are used for email communication for sending and receiving emails.

- IP:
It is the most common protocol used in internet to identify a particular system. It is used along with TCP in internet (TCP/IP).

- TCP:
It is connection oriented protocol i.e. connection is maintained throughout communication. It provides reliable transmission so it is slower than UDP. It is the common protocol used in internet for transmission of hypertext documents, files and email message.

- UDP:
It is connectionless protocol. It doesn’t provide reliable transmission but it is faster than TCP. So, UDP is preferred for transmitting real time, multimedia data.

- VOIP:
It is used for transmission of voice signal through internet. It is the cheaper and faster medium of communication mainly for a long distance.