List all users in ORACLE

Oracle provides a default View to list all available users in database.


ALL_USERS [It lists all users visible to currently logged in user]

e.g.
      select * from ALL_USERS



DBA_USERS [It lists all users available in the database]

e.g.
      select * from DBA_USERS


USER_USERS [It lists the current user]

e.g.
      select * from USER_USERS