Discuss various Network protocols.

The network protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.

The various network protocols are as follows :

1. HTTP (Hypertext Transfer Protocol) — HTTP is the set of rules for transferring hypertext on world wide web. It is an application level protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems. It is a generic, stateless, object-oriented protocol which can be used for many tasks, such as name servers and distributed object management systems. The HTTP protocol consists of two fairly distinct items : the set of requests from browsers to servers and the set of responses going back to the other way.

2. HTTPS (Hypertext Transfer Protocol Secure) — HTTPS is a secure version of HTTP protocol that uses the SSL/TLS protocol for encryption and authentication. HTTPS sends the data in encrypted form to make the transmission secure.

3. FTP (File Transfer Protocol) — FTP is a standard for the exchange of files across internet. Files of any type can be transferred through it. FTP is also the name of a program or command. The objectives of FTP are to encourage indirect or implicit use of remote computers, to shield a user from variations in file storage systems among hosts.

4. TCP/IP (Transmission Control Protocol/Internet Protocol) — It is the base communication protocol of the Internet. TCP is responsible for full-fledged data connectivity and transmitting the data end-to-end by providing other functions, including addressing, mapping and acknowledgement. IP is responsible for obtaining the address of the computer/device to which data is being sent.

5. SLIP/PPP — SLIP (Serial Line IP) was the first protocol for relaying IP packets over dial-up lines. It defines an encapsulation mechanism, but little else. There is no dynamic address assignment, link testing, or multiplexing different protocols over a single link.
   PPP (Point to Point Protocols) is the internet standard for transmission of IP packets over serial lines. It is a data link protocol commonly used in establishing a direct connection between two networking nodes and enabling IP communication over this direct connection.

6. Protocols used by email — The protocols mainly used with email accessing are IMAP, POP3, SMTP and HTTP.

   1. IMAP (Internet Message Access Protocol) is a standard protocol for accessing email from local server.
   2. The POP3 (Post Office Protocol 3) provides a simple, standardized way for users to access mailboxes and download messages to their computers.
   3. The SMTP (Simple Mail Transfer Protocol) is used when we send email to another email users. This can be used to send emails, not to receive them.
   4. HTTP protocol is not a protocol dedicated for email communications, but it can be used for accessing mailbox. Also called web based email, this protocol can be used to compose or retrieve emails from an email account. Hotmail, Gmail are examples of using HTTP as an email protocol.