sessioncookie

A sessioncookie, commonly referred to as a session cookie, is a type of HTTP cookie used to maintain state across multiple requests during a browser session. It is typically stored in memory and is expected to be deleted when the browser is closed, though behavior can vary by browser and user settings. A sessioncookie usually contains a session identifier that references data stored on the server, rather than storing the full user session data on the client.

How it works: when a user authenticates or starts an interaction that requires state, the server issues a Set-Cookie header with a session identifier. The browser sends this cookie with subsequent requests to the same site, allowing the server to retrieve the corresponding session data and respond accordingly. The actual session information is usually kept on the server, while the cookie merely acts as a key.

Persistence and scope: unlike persistent cookies, a sessioncookie has no expiration or max-age attribute in standard usage, so it is not retained long-term after the browser closes. The Domain and Path attributes, along with Secure and HttpOnly flags, define where the cookie is sent and how it can be accessed. Subdomain handling and cross-site policies are governed by these attributes and by SameSite settings.

Security considerations: HttpOnly prevents access from client-side scripts, reducing XSS risk. Secure requires transmission over HTTPS. SameSite mitigates CSRF by controlling cross-origin requests. Server-side storage of session data reduces exposure if the cookie is compromised, but session fixation and interception remain concerns, so proper lifecycle management and timely expiration are important.

Applications and limitations: sessioncookies are widely used for authentication, shopping carts, and user personalization. They are effective for maintaining state with server-held data but rely on secure handling and proper configuration to minimize security risks.