What is deployment for? The API application we wrote earlier just runs the code on the local machine. Using one of the ports on the local machine, we can send the request from the client to the local server. This is good for development purpose. We can quickly test and adjust our application in a development environment. However, our local machine is not intended to be a server; others can't access it. And they cannot send HTTP requests to APIs hosted on our local machine.
If we want to open this API service to external users, we need to host it on a server. The server should be connected to the internet, with a domain and URL that allow others to access it.
Moving an application from a local machine to a server that runs on the internet is called deployment. This will involve work such as environment setting, dependent package installation, and building a web server.