SAP users are classified according to their purpose of access and the way they interact with the system.
.jpeg)
1. Dialog User (A)
User Type: A
Dialog User is a normal end-user account used by people to log in to SAP and perform interactive business transactions.
Purpose: Interactive login (human users)
◾ Used by end users, consultants, admins
◾ Can log in via SAP GUI / Fiori
◾ Password + validity checks apply
◾ Most common user types
Example: Normal End Users/SAP-Consultants
2. System User (B)
User Type: B
System User Type is a technical user mainly used for background processing and system-to-system communication, not for interactive logins.
Purpose: Background works & RFC communication
◾ No interactive logon
◾ Used for system-to-system communication
◾ Password does not expire
◾ Used in ALE, RFC, IDoc scenarios
Example: RFC users between ECC ↔ BW, SAP ↔ SAP.
3. Communication User (C)
User Type: C
Communication Type User is a technical user mainly used for external system communication where interactive logon is not required, but secure, controlled access is needed.
Purpose: External system communication
◾ No GUI login
◾ Password expiry optional
◾ Used by middleware, external apps
◾ Preferred over System users for external access
Example: SAP ↔ third-party application
4. Service User (S)
User Type: S
Service User in SAP is a technical user account used for system-to-system communication, interfaces, and background processing.
Purpose: Shared / anonymous access
◾ Multiple users can log in with same ID
◾ No password expiry
◾ Limited authorization recommended
◾ Audit risk if misused
Example: Internet users accessing SAP via portal
5. Reference User (L)
User Type: L
A Reference User is a template user used to assign additional authorizations to other users. User type cannot log in. This user type is used when the Authorization profile assignment limit exceeds 312 profiles for a user.
Purpose: Authorization inheritance
◾ Cannot log in
◾ Used to assign authorizations to other users
◾ Reduces role maintenance effort
Example: Shared authorization templates