Let's start at the beginning. XML is important in any number of ways. For starters, it complements the weaknesses of HTML, which already is stretched beyond its limits. For instance, in a commerce application it would be great to have tags for and , while technical industries might like a tag. XML will make that possible.
Web designers can better store, manage and lay out Web documents.
I'd wager its value as a document-centric language will come in second to its power as a data exchange format. HTML, and now Dynamic HTML, may have shortcomings, but for the Web-user interface they will remain king. Indeed, just as HTML launched a million Web pages, XML will launch a like number of Web applications and transactions. Most likely, closed environments like intranets and extranets will use it first to streamline commerce and transaction apps. Broad browser support will come next, probably by the middle of next year.