Cookies are text files stored on the client computer and they are kept for various information tracking purposes. JSP transparently supports HTTP cookies using underlying servlet technology.
There are three steps involved in identifying and returning users -
Server script sends a set of cookies to the browser. For example, name, age, or identification number, etc.
Browser stores this information on the local machine for future use.
When the next time the browser sends any request to the web server then it sends those cookies information to the server and server uses that information to identify the user or may be for some other purpose as well.