Dynamic HTML is made up of four interlocking parts. The first is called dynamic styles. Dynamic styles allow you to change the style of any HTML page element on the fly, such as text, cursors, and other objects in cascading style sheets. If you aren't familiar with CSS, it allows you to position text and other elements exactly on a page, and lets you define individual styles for certain text blocks. With dynamic styles, you can automatically change the position of elements on a page, show or hide text, or change the size, color, and other properties of screen text. For example, you could have links automatically change color with a mouseover, or show text when you move your mouse over a certain blank space. Dynamic styles may provide for more flashy special effects in your page, but they do require you to put most things in style sheets, a time-consuming task for those unaquainted with the process.

The next item on the DHTML menu is positioning. What positioning does is all in its name: It allows you to position HTML elements exactly on the page, using x, y, and even z (3D) coordinates to define placement of objects to the pixel. By placing objects in different z-planes, you can overlap objects and specify which is to be placed on top. You can also wrap text around images, and reposition it automatically. Perhaps the most useful application of positioning for interactive sites is that, when used with various scripts, positioning can be used for animation of the page. For an amazing example, check out Microsoft's own Dynamic Asteroids

For embeding specialized data on a page, DHTML data binding provides a reasonable solution. Before, normal HTML pages had to contact the originating Web server and/or database server to allow the user to rearrange the data on their page. But data binding lets authors embed a data source on a page, which users can sort and filter like a database without contacting the original database server. For sites looking to reduce the load on their database servers, this feature is a greatly needed tool.

The last and probably most important DHTML feature for most sites is dynamic content. With dynamic content, web designers can dynamically change the content of an HTML page. This capability can be used to insert or hide elements in a page, as well as to modify the text of individual elements. For example, a script can scan the elements of a page and, using dynamic content, insert a table of contents at the beginning of the page. Web authors can make the table of contents "live", using links to bookmarks. Unlike other browsers that restrict content changes to download time only, these changes can be made at any time, even after the entire document has been downloaded. Dynamic content, in combination with various forms of scripting, can provide for incredible interactivity.