HTML 5 is the newest specification for HTML, and many browsers are going to start supporting it in the future. One nice thing about HTML 5 is that it attempts to stay backwards compatible.
If you build Web applications you will eventually want to learn HTML 5. There are a lot of new attributes and tags built just for Web applications. For instance, there are a number of new event handlers for drag and drop:
And many more. At this point in time, there is not a lot of support for HTML 5, but that support is growing all the time. By staying abreast of the changes you'll be prepared when they become widely available for use.
HTML5 breaks down the barrier between HTML and scripting. HTML5 turns out to be very script intensive. It has a bunch of new elements and attributes, but the major push in HTML5 has to do with features that you can access only through scripting.
Drawing With the Canvas Element
The Canvas element has been long awaited. As its name implies, you can use this element to draw on, and that can mean drawing some complex figures. You can draw lines, circles, arcs, rectangles, curves, and more. You can color figures as you like them and even insert images.