Basic Knowledge of API & API Testing

What is an API?

An Application Programming Interface (API) is a set of rules that lets different software systems communicate with each other — typically by sending requests and receiving structured responses (often in JSON or XML) over HTTP.

What is API Testing?

API testing verifies that an API's endpoints behave correctly — returning the right data, the right status codes, and handling errors appropriately — without going through a graphical user interface.

Why API Testing Matters

• It tests business logic directly, closer to where the real functionality lives.
• It is typically faster and more stable than UI testing.
• It can catch defects earlier, since APIs are often built before the UI.