Can you give an example of when and how API is used in real development?

API (Application Programming Interface) is a set of rules and interfaces for interaction between programs.

In real development, APIs are often used for integration with external services. For example, in web development, REST API can be used to fetch data from a server.

Example: a mobile app requests weather data via a weather service API.

GET https://api.weather.com/v3/wx/conditions/current?apiKey=YOUR_KEY&format=json

The response comes in JSON format, which the app parses and displays to the user.

In QA automation, API tests verify the correctness of such interfaces by sending requests and checking responses without the need to use UI.