A cookie is a small text file that is stored on the user's computer when they visit a website. This file contains information such as the user's preferences, login details and navigation information.

Cookies are used to enhance the user's experience on a website by allowing the site to remember certain information about the user, such as favourite items or language preferences. They are also used to track the user's browsing habits and provide targeted advertising.

It is important to note that cookies can be blocked or deleted by users and that websites must comply with data privacy laws and regulations.