A music production company's function is exactly what its name implies: A company that creates and produces music for diverse clients and projects. Some music production companies will be responsible for artist development and promotion, some for creating musical tracks for rappers and singers to record to (beat making), and others for tv/film music production.
Music production companies are most often set up with music producers as the employees and music content as the end product. Producers can either sign exclusive employment contracts with the company or can be hired as temporary freelance employees. A production company often will hire a producer and allow her to bring on board, and collaborate with, new writers and talent to create a wide variety of music. The company's CEO or owner hires the producers and signs new artists, often by recommendations from producers.
Music production companies can help artist obtain recording contracts since they typically supply highly marketable music to record labels. Major and independent record labels are often overwhelmed by numerous unsolicited demo tape and CD submissions, so a reputable music production company may have a better chance at pitching a new artist. Music production companies may be responsible for live show development, photo shoots, and recording demos, as well as the promotion and marketing of an artist. An artist will typically sign an exclusive contract with this kind of music production company for one to two years.
Particularly for hip hop music, a group of beat makers (producers that create musical tracks without vocal melodies) will form a production company to create higher quantities of tracks. Normally each producer and beat maker will specialize in one genre or "lane" of music. For example, one producer may be better at creating R&B ballads while another is better at making dance and electronic beats. Artists can purchase exclusive rights to use and record tracks from these music production companies.
The sole function of some music production companies is to create music for television shows and movies. Often, these companies, sometimes known as "stock" companies, have direct relationships with music library companies that distribute music to be placed in a show or film. This style of music is more functional than marketable because a music supervisor is not necessarily looking for a hit, but rather a musical track that conveys a certain emotion or mood. Musical tracks for TV or films are often chosen evoke tension and anticipation in the listener.
Music production companies, including beat-making and tv/film music production companies, can advance an artist's career, but the responsibility of promotion ultimately lies with the artist. While a production company can offer important services and open up new doors, artists and producers must take ownership of their own careers and be willing to self-promote to achieve success.