sessionStorage is a web storage feature that allows websites to store data in a user's browser for the duration of a single session. This means that the data is available as long as the browser tab is open. Once the tab is closed, the stored data is deleted. It is useful for keeping track of user preferences or temporary information without affecting other sessions. Unlike localStorage, which retains data even after the browser is closed, sessionStorage is designed for short-term storage. It can hold key-value pairs, making it easy for developers to manage data during a user's visit to a website.