Type of Users in SAP system

In this article discussing about  types of Users in SAP System
here 5 types of users in SAP 

1. Dialogue
2. System
3. Communication
4. Service
5. Reference
  1. Dialogue:-
For this kind of users:-
GUI login is possible.
Initial password and expiration of passowrd are checked.
Multi GUI logins are checked.
Usage:- These are used for GUI logins. 

2. System
For this kind of users:-
GUI login is not possible.
Initial password and expiration of passowrd are not checked.
Usage:- These are used for internal use in system like background jobs. 

3. Communication
For this kind of users:-
GUI login is not possible.
Users are allowed to change password through some software in middle tier.
Usage:- These are used for login to system through external systems like web application 

4. Service
For this kind of users:-
GUI login is possible.
Initial password and expiration of passowrd are not checked.
Multiple logins are allowed.
Users are not allowed to change the password. Only admin can change the password
Usage:- These are used for anonymous users. This type of users should be given minimum authorization.
5. Reference
For this kind of users:-
GUI login is not ible.
Initial password and expiration of passowrd are not checked.
Usage:- These are special kind of users which are used to give authorization to other users.