what is canvas in android

 
Canvas is graphics component in android which does the job of calling Draw method and drawing the shape.

According to android documentation , The Canvas class holds the “draw” calls. To draw something, you need 4 basic components: A Bitmap to hold the pixels, a Canvas to host the draw calls (writing into the bitmap), a drawing primitive (e.g. Rect, Path, text, Bitmap), and a paint (to describe the colors and styles for the drawing).
 
** UPDATE: Android Complete tutorial now available here.