What is API?

An API (Application Programming Interface) is a set of rules and protocols that allows one software application to interact with another. It defines the methods and data formats that applications can use to communicate with each other, whether they're on the same machine or over a network.
For example, when you use a mobile app to check the weather, that app communicates with a weather service's API to request weather data, which is then displayed in the app. APIs can simplify how different systems work together, making it easier to build applications that leverage third-party services, like Google Maps or payment gateways.