This occurs when the casting director and the producer compile a list of the types of actors they need for their production. This list is then sent to different agencies who then try to find matches with the actors they represent. After the closest matches are found, the agent sends portfolios of the actors who they think best fit the roles. Such portfolios may contain a resume, photographs or video footage of past performances.
The casting director sifts through all the submitted portfolios and decides which actors to invite to audition: this part of the process is termed a "callback." The casting director may also send portions of the script to the agent that the actor should read from during the audition: these are termed "sides." Sometimes, a casting director may ask an actor to give a cold reading during the audition in which they read unmemorized portions of the script.
An audition is basically an interview for the open part. It requires the actor to perform a portion of the script in front of the casting panel, which includes the casting director, producer and possibly, the director. Some actors may have monologues memorized that display different aspects of their talent. An actor should be prepared to bring a few copies of hi resume to each audition and also a portfolio for the casting panel.
Background casting involves the casting of non-principal performers in a film. This includes non-speaking roles and extras. The background casting director may also submit a breakdown to different agencies. But, since no speaking is required from these actors, auditions are usually not necessary. A background casting director may also be responsible for coordinating efforts to find extras outside of agencies.