What Are Session Cookies?

Session cookies are temporary cookies that help a website maintain continuity during a browsing session. They let the website connect separate page requests to the same browser.

For example, when you add an item to a shopping basket and open another page, a session cookie can help the website retrieve the correct basket. The cookie often contains an identifier, while the basket details remain on the website’s server.

Session cookies have no expiry date or maximum lifetime set through Expires or Max-Age. They normally disappear when the browser session ends, but there are two important qualifications:

• Closing a single tab does not necessarily end the browser session.

• A browser’s session-restore feature may restore session cookies when it reopens.

A session cookie is also different from a login session: the server can sign you out after inactivity even while the cookie remains. Unlike persistent cookies, session cookies are not intended to remain until a specified future expiry. Their temporary nature does not automatically make them strictly necessary cookies.