A buddy is a backgammon friend on FIBS. You can mark players as buddies, and when they log in you will be notified with a sound.

To make someone your buddy, select the player, then check the "Buddy" checkbox in the Inspector window. Your buddies are shown in boldface in the Player window.

Note that this buddy information is just for you, no one else will see who is or is not marked a buddy by you.