What is a cookie in the context of web browsing?

In the context of web browsing, a cookie refers to a small file stored on a user's device by the web browser while visiting a website. This file contains data about the user's activity on the site, such as login details, preferences, and browsing history. Cookies serve various functions, including enabling websites to remember user information during subsequent visits, which enhances user experience by personalizing content and maintaining sessions, even after the user navigates away or closes their browser.

When a user revisits a site, the cookie is returned to the server, allowing the website to recall the stored information, which can help in tracking user behavior, managing user sessions, and sometimes targeting advertisements based on previous interactions. Thus, in web development and online user experience, cookies play a vital role in facilitating and optimizing interactions between users and websites.