HTTP

http is the most important module of Node.js. It helps you to spin up a server that will listen to one specific port. It will let you transfer information over Hypertext Transfer Protocol (HTTP).

The createServer function takes one function as a parameter, which will be called when you make any request to the server. That function has two parameters: req and res. The first, the request parameter, is a stream that holds all the details of the request. For instance, if you are using a POST request to submit a form, then this object will hold all the values in it. The response parameter is also a stream, and you can use it to update the response header, status, and more:

res.writeHead(200, {'Content-Type': 'application/json'});

Here, you are updating one key in the header and writing the status code as 200, which is "OK." The difference between a parameter and a query is highlighted in the following figure:

Figure...