Whats the difference between union & non-union?

Question

Ive been looking at audition & casting call pages, & it either says "union" or "non-union".

& when it also says union:SAG.

What does all this mean??

Answer 1

SAG is the Screen ACtors Guild the actor's union for film.  Union work is supervised by SAG, they make sure the working conditions are right and the pay is equitable for the work.  Non union work is usually non paying. You have to be a union member to work union.

Answer 2

How do you get into the union?