A company in the business of creating advertisements, packaging and names for products and services, as well as providing marketing and merchandizing advice and general business and promotional counsel to its clients.
A company that represents models, actors and talent of any kind. A modelling agency is responsible for representing and promoting its roster of models and booking jobs for them. Modelling agencies usually handle contracts, payments and the whole business side of the model's life. Sometimes, especially with larger agencies, the agency will "lend" the model money for a photo shoot, comp cards, clothes, an apartment, etc. The agency will then pay itself back by taking money out of the model's first earnings. It is MOT usual for reputable agencies to charge a 'sign-up' or 'joining' fee, or to charge for test shots - if they feel you have potential as a model they will be eager to sign you.