Reusable identity refers to the ability to use the same identity across multiple systems or applications. This means that instead of having a separate identity for each application or service, a user can use a single identity that is recognized across all of them. Reusable identity is important because it can simplify the user experience by reducing the need for multiple logins and passwords, and it can also improve security by ensuring that the user’s identity is consistently and accurately represented across all systems and applications.