Website Cookie Testing Part I

What is Cookie?

Cookie is small information stored in text file on user’s hard drive by web server. This information is later used by web browser to retrieve information from that machine. Generally cookie contains personalized user data or information that is used to communicate between different web pages

Why Cookies are used?

Cookies are nothing but the user’s identity and used to track where the user navigated throughout the web site pages. The communication between web browser and web server is stateless.

What if you want the previous history of this user communication with the web server? You need to maintain the user state and interaction between web browser and web server somewhere. This is where cookie comes into picture. Cookies serve the purpose of maintaining the user interactions with web server.

e.g. In any shopping related website you might have observed if you add any product to cart and left the browser,next time when you open shopping site same product will be aleardy exists in cart.
That means this site store information in cookies.

How cookies work?

The HTTP protocol used to exchange information files on the web is used to maintain the cookies. There are two types of HTTP protocol. Stateless HTTP and Stateful HTTP protocol. Stateless HTTP protocol does not keep any record of previously accessed web page history. While Stateful HTTP protocol do keep some history of previous web browser and web server interactions and this protocol is used by cookies to maintain the user interactions.

Whenever user visits the site or page that is using cookie, small code inside that HTML page (Generally a call to some language script to write the cookie like cookies in JAVAScript, PHP, Perl) writes a text file on users machine called cookie.
Here is one example of the code that is used to write cookie and can be placed inside any HTML page:

Set-Cookie: NAME=VALUE; expires=DATE; path=PATH; domain=DOMAIN_NAME;

When user visits the same page or domain later time this cookie is read from disk and used to identify the second visit of the same user on that domain. Expiration time is set while writing the cookie. This time is decided by the application that is going to use the cookie.Continue- Website Cookie Testing Part II