Cookies are small files that websites place on your computer's hard drive when you visit them for the first time.
Cookies can help you be more efficient. Have you ever inserted an item in a shopping cart in a virtual online store and, after a few days, upon returning, found that the item was still suitable? Here is an example of the function of cookies.
Cookies allow you to store preferences and usernames, register products and services, as well as personalize pages.
However, if you never register or leave personal information on a website, the server will only know that someone with your cookie has returned to the website. You don't know any other information.
The role of a cookie is to indicate to the web server that you have returned to a certain page / site, so that the information previously provided can be retrieved and allow you to use the site features previously used. For example: