What is a cookie?

A cookie is a very small file that contains only letters and numbers (ie plain text) and is stored by browsers. Cookie is used by almost every website, it is required for many web site features, such as sign-in or purchasing. If you do not accept cookies, you basically exclude yourself from using a lot of websites.

I do not want to allow cookies

In this case, you can disable either accept all cookies, even for a single site in the browser settings. At the same time, it will be impossible to use a lot of web pages.