What are cookies?
Cookies are small files that are put on your computer hard disk drive when you visit websites.
Think of a cookie as an identification card that's uniquely yours. Its job is to notify the site when you've returned. While it is possible to misuse a cookie in cases where there is personal data in it, cookies by themselves are not malicious.
Cookies can help you be more efficient. If you have ever put something in a virtual shopping basket in an online store and then returned a few days later to find that the item is still there? That's an example of cookies at work.
Cookies let you store preferences and user names, register products and services, and personalise pages.
But if you never register or leave personal information at a site, then the server only knows that someone with your cookie has returned to the website. It doesn't know anything else.