Cookies allow websites and servers to distinguish your browser from other browsers that store different cookies and to recognize each browser by their unique cookie ID.
If you choose certain settings on your site, the cookie will allow the site to remember those settings the next time you visit it.
Alternatively, when you sign in to a website, it may use a cookie so that the site can later recognize your browser without having to sign in again.
Cookies also allow websites to collect user activity data, such as how many unique visitors a page receives per month. All of these uses of cookies depend on the information stored on them.