The initial version of HTTP had no version number; it was later called 0.9 to differentiate it from later versions. HTTP/0.9 was extremely simple: requests consisted of a single line and started with the only possible method GET followed by the path to the resource. The full URL wasn't included as the protocol, server, and port weren't necessary once connected to the server.
GET /mypage.html
The response was extremely simple, too: it only consisted of the file itself.
<html> A very simple HTML page </html>
Unlike subsequent evolutions, there were no HTTP headers. This meant that only HTML files could be transmitted. There were no status or error codes. If there was a problem, a specific HTML file was generated and included a description of the problem for human consumption.