Advance XHTML Programming Question:

HTTP (Hyper-Text Transfer Protocol) is an Internet communication protocol, that allows a viewer's computer talking to a publisher's computer to fetch XHTML documents.

The viewer's computer issues a HTTP request message to the publisher computer first. Then the publisher returns a HTTP response message back to the viewer's computer with the requested XHTML document included in the message.

The following diagram shows how HTTP works with XHTML documents:
HTTP Diagram