API – Application Programming Interface

is a set of rules and protocols that allow different software applications to communicate and exchange data.

Bridges services, data, and features to other applications.
Creates new business opportunities by combining application features and data
The most commonly used API technologies are:
RESTful API: Based on REST principles. Uses HTTP methods (GET, POST, PUT, and DELETE)
GraphQL API: Uses a single endpoint to receive queries (HTTP, GraphQL).
SOAP API: Uses the SOAP protocol. Uses XML, and is more reliable and secure than REST API.
HTTP APIs are usually firewall friendly.
NOTE: There are also library APIs, but they can only bind to the same technology.