...and the Microsoft AJAX Library, err, and the ASP.NET AJAX Control Toolkit. Yep, Microsoft has not only finally come up with an official name for the AJAX technologies which until now have been known collectively as ‘Atlas’ but has also split it into three individual products. All are expected to ship by year-end.
ASP.NET 2.0 AJAX Extensions cover the server-side functionality, while the Microsoft AJAX Library handles the client-side stuff and integrates with the server-based extensions, naturally. The final part of this triumvirate is the self-explanatory ASP.NET AJAX Control Toolkit.