What is cookies?
A cookie file is a kind of small text file that is saved in your computer when you are on a site. The cookie file remembers the stuff you do on a site, so the next time your arrive at the site it picks up your cookie file to make it easier for your, for example not having to enter your password again.
If you don’t want any cookies stored on your computer you can do that by changing the settings in your browser. Here’s some useful links on how to do it in Chrome, Firefox, Safari, Edge.