The HyperText Transfer Protocol (HTTP) is a data communications protocol and acts as the foundation of the World Wide Web. It was released in 1991 and originally did not have a version number associated with it. Later, it was referred to as version 0.9 (HTTP/0.9) to distinguish it from future revisions.
Request methods and usage
The sole HTTP request method available was HTTP GET, which only included a path to the resource. Unlike future revisions of the protocol, the full URL was not included because the protocol version, server, and port were redundant and therefore unnecessary after a connection was made. There was no support for HTTP header fields in the HTTP request.
The HTTP response included only the requested resource, which was always a Hypertext Markup Language (HTML) file. There were no HTTP header fields in the HTTP response, and no HTTP status codes existed to indicate success, error, or otherwise. If an error occurred then the server will generate a situation-specific HTML file that the client will present to the user to describe the issue.
In the following example, the client is assumed to have connected to a server and requests an HTML file. The server successfully processes the HTTP request and responds with the contents.
<html> Welcome to the example.ai homepage! </html>
HTTP/0.9 was the original release and it was extremely simple, supporting only the HTTP GET method. Only HTML files were included in HTTP responses, there were no HTTP headers, and there were no HTTP status codes.