Cookies are small text files that are placed on your device (computer, tablet, or smartphone) when you visit a website. They are widely used to make websites work efficiently, provide a better browsing experience, and supply information to the website operator.
Cookies can be "persistent" (remaining on your device until they expire or you delete them) or "session" cookies (deleted when you close your browser). They can be set by the website you are visiting ("first-party cookies") or by third-party services that operate on the website ("third-party cookies").