The CANVAS tag is new in HTML5.
DTD: HTML5: <!doctype html>
CANVAS Web Browser Support:
CANVAS HTML Versions
Global attributes, event attributes and:
CANVAS End Tag:
Text to display if the CANVAS tag isn't supported.
Tags valid as content: Flow elements, Phrasing elements plus character data
Tags valid as container: Flow elements, Phrasing elements
CANVAS Special Notes:
By including text inside the start and end tags, you can alert older browsers that they are not getting the full features of the page. This is something like alternative text for images.
More CANVAS Information:
- HTML 5 Canvas Tag Tutorial
- Drawing Rectangles on an HTML5 Canvas Element
- Why Use HTML5 Canvas
- How is the CANVAS Element Different from SVG and Flash
- Is There a 3d HTML 5 Canvas Context?
- Basic Canvas Examples