public Role

The public role is a special database role to which every database user belongs. The public role:

• Captures all default permissions for users in a database.
  
  
• Cannot have users, groups, or roles assigned to it because they belong to the role by default.
  
  
• Is contained in every database, including master, msdb, tempdb, model, and all user databases.
  
  
• Cannot be dropped.