This article tells about cookies and why and how the web developer use these cookies.

Cookies are used to store user specific information in form of text strings on the hard disk of user. When a user visits particular website some user specific information gets stored and this information can be retrieved later when the same website gets visited from same machine and can be sent to corresponding server. Cookies are associated with websites instead of individual pages of web site.For eg. with www.example.com not with www.example.com/xyz/abc.html.

Some web developers use cookies to maintain sessions of user on their websites.If you have disabled cookies for your browser then these websites wont work .Web developers also use cookies to store user preference and renders the customized page on next visit according to user's interest. Cookies can also be used for demographic statistics and can store info about what is in your basket for online shopping site and there by they can determine your interests and can make your interest profile over a period of time. There are browser imposed limitations regarding size of cookies and number of cookies per website which can be stored.

However user can disable and delete cookies at any time so developer has to take care of this issue while developing website.