Confluence: How is a Confluence user defined?
What kind of users are activated when buying a license?
A user is, by definition, any account with the permission to log into the application.
A named user with this permission is counted towards the user limit, whether logged into the application or not. So a user is defined by an e-mail address and a password.
However, it is possible for anonymous users (without an account) to access Confluence pages and spaces, if these pages and spaces are open for public access.
In Confluence cloud, user management is centralized and you can implement SAML in order to enable your users to authenticate through your company's identity provider.