I just got the comment "I think that the webmaster means exactly what it says, being a master of the web." But what does that really mean? If you make the assumption that the W3C is a good representation of what is on or possible on the Web, then there is an awful lot to "master". If you go just by their A to Z list, you need to master things like accessibility, CSS, HTTP, P3P, XHTML, XML, as well as lots of other things.