canvas : new HTML 5 Tag element

The canvas tag is only a container for graphics, you must use a script to actually paint graphics.
It is a new tag which implemented in new html version. which allows to render the graphics and bitmap images for dynamic scripts.
It is not very difficult as well as not very easy...U must and should need to know the basicsof HTML n Java script to work on.
It is a purely browser dependent HTML tag which may not probably works in Internet Explorer.
Apple Company introduced for their own product and component called Man OS X Webkit., and Safari Browser. Now it was adopted to Open Source browsers like Firefox and Mozilla(Gecko browsers). Works fine in OPERA browser too.

Can be used to draw graphics using Javascript. And also used to draw graphs and to make photo compositions, animations, games.

Links:
http://www.w3schools.com/tags/html5_canvas.asp
https://developer.mozilla.org/en/Canvas_tutorial
http://developer.apple.com/documentation/appleapplications/conceptual/safarijsprogtopics/tasks/Canvas.html
http://www.brandspankingnew.net/archive/2005/09/the_canvas_tag.html
http://www.whatwg.org/specs/web-apps/current-work/
https://developer.mozilla.org/en/Canvas_tutorial