Cookies in themselves are not a complete solution for authentication and authorization. They are primarily used as a tool to maintain a session state between a client and a server in a web application. When a user logs in, the server can create a session and store a session identifier in a cookie, which the client sends back to the server with subsequent requests. This is where their role in authentication begins.

However, by themselves, cookies do not authenticate or authorize a user. Cookies must be used in conjunction with secure authentication methods, such as username/password combinations, OAuth, OpenID Connect, or other token-based systems, to identify and verify user identities. Once authenticated, the server assigns an identifier (stored in the cookie) to keep track of the user’s session.

In terms of authorization, cookies alone do not manage permissions or roles. After establishing the user’s identity, the application must enforce authorization rules based on the user’s roles and permissions identified either during or after authentication. This could involve server-side logic to determine what resources or actions a user is permitted to access.

Additionally, it’s crucial to secure cookies properly to avoid vulnerabilities such as session hijacking and cross-site scripting attacks. This involves using flags like HttpOnly, Secure, and SameSite, which help mitigate security risks associated with cookies.

In summary, cookies are a part of the authentication and authorization process in web applications, but they must be paired with secure authentication techniques and authorization logic to effectively and securely implement these functions.