Single Sign-On (SSO) is an authentication process that allows users to access multiple applications or services with a single set of login credentials. Instead of managing separate usernames and passwords for each platform, users authenticate once and gain seamless access to all connected systems. SSO enhances user convenience, reduces password fatigue, and improves security by centralizing authentication. It is commonly used in enterprise environments to streamline access to cloud services, internal tools, and third-party applications.