A very small text file placed on your hard drive by a Web Page server. It is essentially your identification card, and cannot be executed as code or deliver viruses. It is uniquely yours and can only be read by the server that gave it to you.
To tell the server that you returned to that Web page.
It saves you time.
If you personalize pages, or register for products or services, a cookie helps remember who you are.
It allows us to be more efficient. We can learn what information is important to our visitors, and what isn’t. We can discard Web pages you don’t use, and focus our efforts on information you need.