One of the most common questions I get from actors is "What is avail?" Its a funny thing. I will try to explain as best as I can.
When an actor goes on a first audition it is usually just a camera man and the actor in the room. The video is reviewed by casting directors and/or the production team. From there and actor may or may not get a "call back."
A call back is a little different than a first call. The actor will do the same thing, but the room will have the camera man, the director, producer and often the ad agency will be present as well. It can be a bit scary with the panel sitting in front of you!
After the call back your video is reviewed again. If they cannot decided between actors you may be place "on avail" until they decide. This way they know that the actor is available to work those shoot days. This is ONE reason for avail. Another reason for avail is that you (the actor) may be the only choice for the job but they do not know the shoot dates yet and will hold you for a longer amount of time to be sure they have you when they figure the schedule out. Another reason for avail could be if the project is not on for sure, or on the verge of being cancelled. Either reason for avail is an accomplishment.
As far as I am concerned a call back is a sign that you are doing something right! Its hard to even get in the door to be seen much less being asked to come back!
So all my actors out there reading should set goals for themselves to start getting called back and always be "AVAIL."