What is a cookie in web development?

A cookie is a small piece of data stored on the user's computer by their web browser while browsing a website. It is created when a user visits a website that uses cookies and can store various types of information, including user preferences, session identifiers, and tracking information. Cookies are essential for maintaining state across different sessions and for personalizing the user experience by remembering user settings or login information.

This function of cookies is foundational in web development, as it allows web applications to provide a customized and continuous experience for users, enabling features such as remembering login credentials, preferences, and items in a shopping cart. The data stored in cookies is sent back to the server with each request, allowing for relevant information to be processed based on the user's previous interactions.

In contrast, a type of JavaScript function, a framework for handling database connections, and a software application for website testing do not pertain to the storage of user-specific data directly by a web browser in the way that cookies do.