FormsAuthentication

FormsAuthentication is a membership and authentication system used in ASP.NET to manage user logins and access control. It allows developers to create custom login pages and handle user authentication based on credentials like usernames and passwords. When a user successfully logs in, FormsAuthentication generates an authentication ticket, which is typically stored in a cookie on the client's browser. This cookie is then sent with subsequent requests to the server, allowing the application to identify and authenticate the user without requiring them to re-enter their credentials for each page visit.

The authentication process typically involves a login page where users submit their credentials. The application verifies these credentials against a data source, such as a database or Active Directory. If the credentials are valid, FormsAuthentication.SetAuthCookie is called to create and send the authentication ticket. The application can configure various aspects of the authentication ticket, including its expiration time, sliding expiration (which resets the expiration on each request), and whether it's persistent.

Authorization, or determining what resources a user can access, is handled separately after authentication. Developers can use the authenticated user's identity to restrict access to specific pages or sections of the application. FormsAuthentication is a flexible system that provides a foundational layer for securing ASP.NET web applications, allowing for custom-tailored security experiences. It is important to note that FormsAuthentication is considered legacy and has been largely superseded by ASP.NET Identity for newer applications, offering more modern features and better extensibility.