DEFINITION: API ABB is an Application Interface constituting the interfaces of various building blocks that a developer can assemble to create an application. An application developer utilises APIs to build an application by combining various available software libraries to achieve a specific goal. Source: Gartner (https://www.gartner.com/en/information-technology/glossary/application-programming-interface) INTEROPERABILITY SALIENCY: IoP Dimension: Structural IoP, Behavioral IoP EXAMPLES: The following implementation is an example on how this specific Architecture Building Block (ABB) can be instantiated as a Solution Building Block (SBB): RapidAPI RapidAPI is a collection of predefined APIs that are free to test, specifically updated for 2021. Source: (https://rapidapi.com/collection/list-of-free-apis)