What is SAG and Equity?
You may have already noticed that some auditions and casting calls are marked as UNION or NON-UNION. There are multiple actor’s unions. The Screen Actors Guild (SAG) and American Federation of Television and Radio Artists (AFTRA), which represent child and adult actors working in film and television, as well as Actors Equity (AEA), which is a union for theater actors. Being part of a union guarantees you a certain pay scale, as well as regulated work conditions. Unions provide you with the support needed if your work contract is violated. Along with child labor laws, they are there to protect young actors and moderate the quality of their work conditions.
It is often thought that becoming a union member prevents you from auditioning for non-union work, however, it’s not necessarily true. You can audition for any role, but you can only work under union contracts. Once you have been cast, your work providers will have to agree to the union contract. You can read more on that on the SAG official website http://www.sagaftra.org/ or on http://www.actorsequity.org/