A primer on HTTP response

To understand the types of response Express is capable of generating and have a better control over them, it is important that you have some technical understanding about the underlying HTTP protocol's response format. So, let's go over it real quick and cover the basics.

Note

HTTP response is a small part of the much bigger HTTP protocol. As a web developer it is an added advantage if you have a good understanding of the protocol you are working with. You can read about the HTTP protocol in detail at http://www.w3.org/Protocols/.

The data sent by an HTTP server in response to a request is called an HTTP response message. It is composed of a status code, headers, and optional associated data, which is technically referred to as the body of the message.

The body is presented to the user as plain text, rendered HTML, image, file download, and so on. The status code and the headers are hidden from a regular user, but the browser requires them to process the body appropriately...