{security-api-url}org/springframework/security/authentication/AuthenticationManager.html[`AuthenticationManager`] is the API that defines how Spring Security's Filters perform <<authentication,authentication>>.
The <<servlet-authentication-authentication,`Authentication`>> that is returned is then set on the <<servlet-authentication-securitycontextholder>> by the controller (i.e. <<servlet-security-filters,Spring Security's ``Filters``s>>) that invoked the `AuthenticationManager`.
If you are not integrating with __Spring Security's ``Filters``s__ you can set the `SecurityContextHolder` directly and are not required to use an `AuthenticationManager`.
While the implementation of `AuthenticationManager` could be anything, the most common implementation is <<servlet-authentication-providermanager,`ProviderManager`>>.
