XML, AJAX and Web 2.0
The web is an ever-changing entity. Not only does the content change, but the technologies behind the web changes at a very fast pace.
Right now, XML is extremely important. You can subscribe to a feed of pretty much any content source (news papers, search results, and even this blog). In addition XML is quickly replacing CSV text files as the preferred means of exchanging data between web sites and applications. If you aren’t using XML in some fashion on your site, then it is behind the times. Every single site I have worked on this year has an XML feed of some sort (not always accessible to the public).
AJAX is another new technology. It is designed to give web applications a feel of a desktop application without extra downloads. I really like AJAX, when it is used logically. For example, Google seems to be using a lot of AJAX with their GMail, Calendar, Spreadsheet, and other applications. Other times I see AJAX applications that just don’t make sense. In the next 2-3 years I think that most mainstream web sites will be using AJAX in some way or another.
Finally, Web 2.0. Web 2.0 is nothing except for a term. Maybe XML and AJAX are items that fall under the Web 2.0 name. I feel that the web is changing technologies so constantly that it is difficult to say when one phase starts and ends. Some people say Web 2.0 is just a term that refers to the trend in new sites that are driven in large by the user. Others say it is little more than slight gradients in the header and slow page loads. I’ll let you be the judge.