Draw Rectangles And Annotate Webpage

What is the best utility/API to use in order to draw rectangles and annotate a webpage within the browser? I need the user to be able to draw a box over the existing HTML content a

Solution 1:

You didn't say what kind of project you are working on, but choose one environment (which supports drawing rectangles over other content) and do everything within that environment. You could, for example, use HTML5 canvas. (If you search through OpenLayers.js a bit, you'll see they did the same)

This is a great resource to get started: http://www.html5canvastutorials.com/