Actors may be interested in working theatrically (stage, film or television) as well as in commercials. Some agents will handle all types of acting work while others may specialize in a particular area. There are agents who represent television, voice-overs, or just film and television. Typically, the larger the agency, the more specialized the agents.

An agent has two sets of clients: the "talent" (actors, models, voice-over artists, etc.) and the "buyer". The buyer can be a casting director, advertising agency, production company, photographer, or direct client if the client has an "in-house" production staff. Agents promote talent to the buyers, submitting talent that have the appropriate age, race, sex, look, talent, etc. that the buyer is seeking for his/her project. Usually, an agent submits the actor's head shot or the model's composite card or portfolio to the buyer. After the buyer has made choices, the agent then arranges an audition (or for models, a "go-see" or open call). After the buyer has met the talent, the buyer will contact the agent if any of the talent will be hired. The agent will coordinate the details of wardrobe, directions, etc. as well as negotiate the contract or pay.

Note that the agent's job is to get the talent auditions; the talent is the only one who can get the job. For their work, agents take a 10 to 20% commission of the gross, depending if the job is union (such as SAG-AFTRA) or not. Union jobs are paid per negotiated guidelines, but sometimes in non-union jobs the pay is delayed.

A well established agent will have networks upon networks of contacts. Also, agents have access to professional casting services. Many of these casting resources are not available to the general public.

Although most of the successful agents are private individuals unknown to the public, some are celebrities in their own right. These notable current and former talent agents include Jadin Wong, Ari Emanuel, Lew Wasserman, Johnny Hyde, Sue Mengers, Freddie Fields, David Begelman, Quincy Sims and Irving "Swifty" Lazar.

In order to qualify as a top modeling agency, there are certain criteria:

1. The agency must be located in a top fashion capital for the simple reason that the most lucrative and prestigious modeling assignments are there. These cities include: New York, Milan, Paris, London, Tokyo, Sydney, Rome, Los Angeles, Prague, Toronto, São Paulo and Barcelona.

2. The agency is well-known and respected in the fashion industry and has a good reputation, insofar, as monitoring agencies or governing bodies in their respective country, like the Better Business Bureau in the US and the association of fashion designers and the group handling the city's fashion week.

3. The agency has directly provided a model with a lucrative assignment for a top fashion design house (for example Gucci, Dolce & Gabbana, Calvin Klein, Prada, Valentino and Giorgio Armani among others).

Some of the top modeling agencies in the world are: