1. Hyper Text Transfer Protocol
HTTP
Hyper Text Transfer Protocol
HTTP is an application layer protocol.(port 80)
When a user types a URL it is automatically prepended with http.
Web pages located at server consists of objects.
Objects can be HTML file or document or images or gifs etc.
So when a user is requesting for a page it is requesting for objects of a webpage.
Each object is addressable by a URL.
When a client is requesting for an object to the server it is known as http request.
When a server replies to the request it is known as http reply.
Client SERVER
http request
http reply

2. HTTP Connections
There are two types of http connections-
Persistent http connections.
Non-persistent http connections.
Persistent http connection : In case of persistent http connection,connection will be there only until all objects are accessed.
Non-persistent http connection: In case of non-persistent http connection,a seprate connection will be established for every individual data transfer.

3. API (Application Programming Interface)
It has got methods like-
Head() - It is used to get the informationn about the document.
Get() - It is used to retrieve the document.
Put() - It is used to modify the document.
Post() - It is used to update the document & send to server.
Trace() - It is used for debugging the network.This is used by the network Analysers.
Connect() - It is used for establishing the connection.
Http uses TCP as a transport layer protocol because the data is reliable.HTTP is a stateless protocol because it does not retain any information about the network.

4. Cookies
Piece of code that is transferred from server to client if we click on some object it automatically sends an authentication.Source IP is send to the server.
Advantages:
Authorization.
Faster Response.
-Cookie is a piece of code that is transmitted from the server to the client browser.
-If the cookie is enabled , computer’s IP Address & authorization number is forwarded to the server.