Cookies got much attention in internet security area in and around 2000. At that time the most popular definition of cookies was like this. Cookies are programs inserted by website on your hard disk when you visit the site. They collect all information related to your activities and it is sent to the website owners. This definition is a wrong and misleading one.
Actually cookies are small piece of text, not programs. Can a simple text collect all the information related to you? Can this simple text communicate automatically with its website owner? The fact is that it cannot collect any information from you. Cookies consist of some Name Value pairs. They are set by the website.
When you visit a site, server set a user id for you and it is inserted in your hard disk. When you visit again this site, the server can recognize you as a previous visitor. If you deleted the cookie, then you will get a new user id and assigned as a new user. Usually user id is collected. But many site are inserting other values like session time and session id too.
How data moves using Cookie?
When you enter a URL, browser will send a request to the corresponding server to retrieve data. For example, when you enter WWW.GOOGLE.COM, the browser will check for cookies related to Google. If it is found, the data in the cookie is send along with request.
There are also options in our browser to remove cookies. Cookies actually provide easy user interface with the website.
