Comprehensive resource on Internet cookies, including what they are, how to block or stop them. When you need to pass some snippet of information to another system to make it do something, how do you do it? If you're on the Web or some other network, you use a cookie. The cookie is a text file saved in your browser's directory or folder and stored in RAM while your browser is running. Most of the information in a cookie is pretty innocuous, but some Web sites use cookies to store personal preferences or tracking data.