The primary advantage of single sign-on (SSO) is that it increases the efficiency of access management. With SSO, users only need to remember one set of credentials to access all of their applications, rather than having to remember multiple usernames and passwords for each application. This simplifies the user experience and helps to reduce the amount of time spent managing access to multiple applications. Additionally, SSO can also increase the security of related applications, as users are not sharing the same credentials across multiple applications, and it can also support multiple authentication mechanisms, such as biometric authentication.