# User authentication elements

You can view the types of elements used for configuring user authentication and directory services and the element descriptions.

Table 1. Types of elements in user authentication configuration
Element Type | Explanation
--- | ---
Authentication Methods | Configured authentication methods for end-user and administrator authentication. Used in rules that require end-user authentication.
Servers | Active Directory Servers, LDAP Servers, RADIUS Authentication Servers, and TACACS+ Authentication Servers for end-user and administrator authentication and directory services.
Users | End users stored in the internal LDAP database or an external LDAP database. Used in rules that require end-user authentication.
Other Elements | SMTP Servers | SMTP servers that send email or SMS messages about changes to user accounts to end users. The same SMTP Servers can also be used to send Alerts to Administrators.