Postman` is an API platform that simplifies each step of the API lifecycle and streamlines collaboration. To use Postman, one needs to create an account, navigate to the workspace, collections, and requests. The user can make a GET request to read data from a data source like I Can Haz Dad Joke API, and also send a POST request with authorization to the Twilio Programmable SMS API. Debugging and reading responses are essential parts of using Postman. Additionally, users can use variables, environments, and scripting in Postman to add testing to their requests and manage multiple variables related to the same project.