Question: I am a junior developer I can't understand how canvas tag is beneficial for us?
I read lot of articles on that but I can't get the root benefit getting from the canvas tag.

Answer: 
Some possible uses for Canvas:

* Image drawing program
* Photo editing/manipulation
* 2D Games
* Advanced image viewing such as [Microsoft's Deep Zoom](http://ie.microsoft.com/testdrive/Graphics/DeepZoom/Default.html)

If you can't understand how it's beneficial, then maybe it isn't from your point of view at least. Don't think that because it's there I have to use it somehow, pick and choose what technologies work for you based on what you're trying to build, an Accounting web app probably wouldn't need a canvas for instance.
my personal take on canvas (and when I actually found a use case for canvas) is the ability to color pick and color change per pixel in a canvas element - actually moving the image from something we don't have any information about what is happening inside it to an element like all other DOM elements (and yes, I know about the current problems with canvas and DOM - sure this would be taken care of in the future)

sure - canvas made some sort of animation easier and pluginless, but that we could do before (mostly with flash) - I think the real importance is the ability to know what is happening on the page.