What cookies are
Cookies are small text files a website stores in your browser. They allow a site to remember information between page loads, such as a preference you set or a session state that keeps a form intact while you type. Without them, every page view would start from nothing and a partially completed action would be lost the moment you navigated away.
Similar technologies, including local storage and session storage, work in comparable ways. They hold small pieces of data on your device and read them back on later visits. Where this policy says cookies, it covers those browser storage methods as well, because the practical question for you is the same: what is being kept, and can you clear it.
In short
A cookie is a note your browser keeps on our behalf. It is not a program, it cannot read other files on your device, and it does not identify you by name unless you have typed your name into a form yourself.