Microsoft has pioneered updatable Web pages since the late 1990s. With Internet Explorer 4.0
(released back in 1997), Microsoft introduced Dynamic HTML (DHTML), which is a powerful
combination of HTML, style sheets, and scripts that allows programmatic changes to any
displayed page. Several companies since then have worked out their own DHTML object
model—often referred to as the Browser Object Model (BOM). The W3C committee worked
hard to bring vendors to agree on an interoperable and language-neutral solution for exposing
Web pages through an updatable programming interface. The result is the Document Object
Model (DOM), as opposed to a browser-specific BOM.
The DOM is a platform-independent and language-neutral representation of the contents of
a Web page that scripts can access and use to modify the content, structure, and style of the
document.
For AJAX, it’s all about exchanging data with a remote server. But once the data is downloaded
out-of-band on the client, what can you do with that? The DOM provides an outlet for the data
to flow into the current page structure and update it.
