Computer Sciencecalendar_todayLast updated: Apr 2026
What is API?
/ˌeɪ piː ˈaɪ/
An API (Application Programming Interface) is a set of rules that allows different software applications to communicate with each other. It defines what requests can be made, how to make them, and what responses to expect.
lightbulb
Everyday Example
When a weather app shows today's forecast, it is using a weather service API — the app asks "what is the weather in London?" and the API replies with the data.
publicReal-World Application
“Stripe's payment API, Google Maps' mapping API, and Twitter's social API are used by millions of developers to add functionality to their apps without rebuilding it from scratch.”
psychology
Did you know?
The concept of an API predates the web by decades — operating systems have exposed APIs since the 1960s so programs could use shared computer resources.
emoji_objects
Key Insight
APIs are the invisible connective tissue of the modern internet. Almost every app you use is stitching together dozens of third-party APIs behind the scenes.
Want to learn API in 60 seconds?
Join 50,000+ learners snacking on knowledge daily.