What the heck is a Cookie?!
A cookie is a tiny file that’s stored on your computer. It contains the address of the web site and codes that your browser sends back to the web site each time you visit a page. Cookies don’t usually contain personal information or anything dangerous; they’re usually harmless and useful.
When you browse the web, the web server needs to know who you are if you want to do things that require logging in or putting items in a virtual shopping cart or completing any other process that requires that the web site remember information about you as you move from page to page. The most commonly used system that allows Web sites to keep track of what you’re doing is called setting cookies.