What does an Application Programming Interface (API) allow applications to do over a network?

An Application Programming Interface (API) serves as a set of rules and protocols that allow different software applications to communicate with each other over a network. The primary function of an API is to facilitate the sharing of data, methods, or functions between applications. This interaction enables developers to build applications that can leverage the functionalities of other software, systems, or services without needing to understand their internal workings.

For instance, when a mobile application accesses data from a web service, it typically does so through an API, which defines how requests for data should be made and how the data will be returned. This capability is essential for developing applications that are modular, extensible, and able to integrate with a wide range of services across the internet.

In contrast, other choices involve roles that APIs do not directly perform. While encryption is essential for secure communication, APIs themselves do not inherently encrypt data; this is performed by other security protocols. Similarly, physical security controls and user access management are typically handled at different layers of the system architecture and not through API interactions. Thus, the ability to share data, methods, or functions through an API is the most accurate description of its purpose in network communication.