To understand the toolkit's value, one must first appreciate the problem it solved. Before the widespread adoption of asynchronous JavaScript and XML (AJAX), postbacks in ASP.NET Web Forms caused the entire page to reload, leading to a clunky, desktop-like experience with noticeable flicker. Microsoft introduced the ASP.NET AJAX extensions to enable partial-page updates via the UpdatePanel . However, the stock offerings were basic. The , an open-source collaboration between Microsoft and the developer community, extended this functionality by providing a rich suite of over 40 client-side enabled server controls.