1. XML is an HTML-like formatting language. Misconception: The recommended advice when developing Internet protocols has been be conservative in what you send and liberal in what you receive. While in the early days this philosophy fostered interoperability, any economist could tell you the long term effect of this. It leads to a large number of slightly incompatible implementations of protocols, all of which mostly work, but none of which interopate well. For example, FTP is one of the oldest Internet protocols, and there are essentially no fully complient clients or servers, and building a fully interopable client/server is extremely difficult, requiring knowledge of all the quirks of all the popular implementations. Therefore, XML has chosen the opposite approach: compliant implementations are supposed to reject all input that isn't "well-formed", even when the intent is clear. This not only avoids interoperability errors in the long run, it also dramatically improves security by guaranteeing that there is only one way to interpret things. From Hacking-Lexicon