What is the <canvas> tag in HTML? and can it be used on it's own meaningfully without any script?

The HTML <canvas> element is used to draw graphics, on the fly, via scripting (usually JavaScript).

The <canvas> element is only a container for graphics. You must use a script to actually draw the graphics.

Canvas has several methods for drawing paths, boxes, circles, text, and adding images.

http://www.w3schools.com/html/html5_canvas.asp

<canvas> tag is used for creating drawings, placing images, animations etc. and It cannot be used  on its own. It must be used with script