Set UID:
SUID permissions are valid only for binary programs
Performer must have X executable permission for the program
This permission is valid only in the course of executing the program
Performer will have permission to host the program
Set GID:
Sgid useful for binary programs and directories
Program performer requires x permission for the program
The performer will receive support for the program group during execution
Users can enter this directory if they have r and X permissions for this directory
A valid group of users in this directory will become a group of that directory
Sticky Bit
This is currently only valid for the directory, the file will not be effective.
When a user has w,x permissions on this directory, they also have write permissions
When a user creates a file or directory under that directory, only himself and root can delete the file or directory
4 for Suid
2 for Sgid
1 for Sbit
Set UID, set GID, Sticky Bit in Linux