SAM, or Security Account Manager, is a database in Microsoft Windows operating systems that stores user account information and security descriptors for users and groups. It plays a crucial role in managing user authentication and access control, ensuring that only authorized users can access specific resources. The SAM database is typically located in the Windows Registry and is protected to prevent unauthorized access. It contains hashed passwords, which means that the actual passwords are not stored, enhancing security. SAM is essential for maintaining the integrity and security of user accounts within a Windows environment.