Nexus Professional's User Account Plugin allows anonymous users to sign-up for a Nexus account without administrative intervention. This "self-serve" capability for user account creation is especially important when an open source project is using Nexus as a primary means for distribution. In such an environment, there may be hundreds of Nexus users who all need a basic level of read-only access, and making these users wait for an administrator to create an account makes little sense. In such a setting, anyone can create an account, activate the account via a verification email, and then access a repository with a default, read-only level of access which you can define.