There are three days left this week, which gives me one a piece to cover the what, why and how of Ajax. Starting with what:
Well, it's not a Dutch football team or a kind of bleach! Ajax is a new name given to something which has been around for a while now, but without it's own catchy moniker.
It's not a new idea and has been possible for a long time. Only now is it becoming more and more feasible to use this approach in anything other than the latest release of IE. Mozilla and Safari now support on-the-fly requests for XML.
Once upon a time you could get away with developing applications solely for use with IE. Not so any more. An increasing number of clients (mine at least) are requesting their applications feature dual support for IE and Mozilla (i.e. Firebird). In the past this would of ruled out the fancy stuff like on-the-fly lookups. With Ajax we can do some truly amazing stuff and rest assured it's going to work in all the latest browser releases. Cool.
Remember last year I talked about ways of preventing conflict documents on the web? The solution I came up with used an XML Island and was very IE-only (download). The same thing can be done with Ajax and work in other browsers too.