Программный интерфейс приложения — набор готовых классов, процедур, функций, структур и констант, предоставляемых приложением (библиотекой, сервисом) или операционной системой для использования во внешних программных продуктах.

Short for application programming interface, refers to a set of protocols through which programmers can access external services (from other programs), which may query proprietary data, access sensors or actuators, or perform computations.

The developer really liked working with that API because it cut down her programming time considerably.

By opening their API, they are hoping to encourage the development of an ecosystem around their product.

His company put together a poor API and received complaints that it was causing some apps to function improperly.