API testing is a type of software testing that analyzes an application program interface to verify it fulfills its expected functionality, security, performance and reliability.
API testing is important for ensuring that your API performs as expected when faced with a wide variety of expected and unexpected requests.
This process is designed to not only test the API's functionality — but also its reliability, performance, and security.
The tests are performed either directly on the API or as part of integration testing.
Furthermore, to perform API testing, do following steps:
Install python installer on your device.
Install pycharm framework on your computer.
Create a new project on pycharm.
Include python installer(64-bit) package in pycharm.
Click on the project and then go to settings.
Add necessary project interpreters including requests, behave and json ect.
Create a file in your project for api testing
Import json and requests interpreters
Include URL for which you want to test the api
Include necessary headers
Write code
Run your file and analyze the result
I am attaching a plyalist link for further clearification: