In our language we use the term agency in a generic way to refer to the companies that carry out business or management activities of various kinds. Thus, if it is in charge of marketing cars we will say that it is a car agency, if it deals with the collection and dissemination of information it will be a news agency, if it is in charge of marketing and promoting a brand it will be an advertising agency If your mission is to represent catwalk models and advertising, we will be in front of a modeling agency, and if your mission is the sale of trips or tourist packages, it will be a travel agency, among other options.
So, if we look for a common point between the proposals of agencies mentioned, we will find that all, beyond the object they pursue, will be in charge of carrying out a commercial activity, that is, they will sell a resource that they have and manage in exchange for a specified sum of money, which will be paid by the person who wants to access that resource or product.
Meanwhile, to sell this resource, the agencies operate in a physical place, such is the case of an office, in which they can carry out this work, and the most important thing is that they will be able to receive the potential consumer there to present them in detail the benefits of what they want to sell you.
Likewise, in the offices, the agencies, have all the material and the characteristics inherent to the service they sell so that the client can appreciate it in situ and if it is possible to choose between the various proposals that exist.
There are some large agencies that even have subsidiaries in other provinces, regions or countries from where they also manage their resources and thus make them spread fabulously. For example, there are modeling agencies that have branches in different countries and then this situation will allow a model that is represented by the agency of her country to get jobs as such but in another country.
Due to what is stated in the previous paragraph is that the word agency in some Spanish-speaking parts is also used as synonym of branch.