The API, or Application Programming Interface, is a set of rules that governs how two separate pieces of software interact. When one piece of software makes a request to the other, it can be said that they are calling an API. More often than not, the interface is the front-facing part of one program, and the back-end part of another - meaning that APIs serve as the bridge between two different applications or systems.

What is an API?​

An API, or application programming interface, is a set of tools and protocols that allow software applications to interact with each other. In the context of testing, an API can be used to verify that two different applications are able to communicate with each other correctly. This is done by sending requests from one application to another and checking that the responses are as expected. API testing is a type of software testing that focuses on verifying the functionality of API calls. This includes testing for correct input and output, as well as error handling. API tests can be performed manually or automated. Automated API tests are often run as part of a continuous integration or delivery process. When writing API tests, it is important to consider what needs to be tested. This will vary depending on the application and the specific API being used. Some things that may need to be considered include:

-Functionality: Are all API calls working as expected?
-Performance: How fast do the API calls execute?
-Security: Are the API calls secure?
-Error Handling: What happens if an error is encountered during an API call?