explain what are cookies?
Cookies have, for some reason, gained a rather sinister image. But they really are simple and harmless. (Note that this question became so popular that HowStuffWorks now has a complete article on cookies.) A cookie is just one or more pieces of information stored as text strings on your machine. A Web server sends you a cookie and the browser stores it. The browser then returns the cookie to the server the next time the page is referenced.