A cookie is a very tiny piece of text a web site asks permission to place on your computer's hard drive. If you agree, then your browser adds the text in a small file. It has various purposes, but is not harmful to your computer.
So why do web sites offer cookies?
Cookies help us evaluate visitors' use of sites, such as what customers want to see and what they never read. That information allows us to better focus a sites online product, to concentrate on information people are reading and products they are using.
And guess what? A cookie can help you.
If you accept a cookie, nothing affects you immediately. But you know what happens whenever you want to download software, access a premium site You get asked questions like who you are and your email address. And that happens every time you want to download stuff from certain sites.
If you have accepted a cookie, however, those questions eventually will be asked just once, no matter how often you download software or how many of that particular sites pages sites you visit.
In the future, a cookie will allow you to tell a site what information you prefer to read and what you don't. If you're a gamer, for example, the web site can advise you on content specific to games.
Cookies are harmless, occupying just a few bytes on your hard drive. They also can be a Web site browser's very good friend.