Catering is the business

Business

A business is an organization engaged in the trade of goods, services, or both to consumers. Businesses are predominant in capitalist economies, where most of them are privately owned and administered to earn profit to increase the wealth of their owners. Businesses may also be not-for-profit...

 of providing foodservice

Foodservice

Food Service or catering industry defines those businesses, institutions, and companies responsible for any meal prepared outside the home...

 at a remote site or a site such as a hotel, public house (pub), or other location.
A mobile caterer serves food directly from a vehicle

Vehicle

A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....

 or cart that is designed for the purpose. Mobile catering is common at outdoor events (such as concert

Concert

A concert is a live performance before an audience. The performance may be by a single musician, sometimes then called a recital, or by a musical ensemble, such as an orchestra, a choir, or a musical band...

s), workplaces, and downtown

Downtown

Downtown is a term primarily used in North America by English speakers to refer to a city's core or central business district ....

 business districts.
Events range from box-lunch drop-off to full-service catering.