The document discusses using the html2canvas library to capture screenshots of web pages and elements on the client side. It provides code samples for capturing a screenshot of a div element, saving it as an image file on the server, and displaying the image. The library builds a representation of the DOM, including images and CSS, and converts it to a canvas element without using screenshots. It has advantages of client-side rendering and on-demand screenshots but limitations around frames, CSS3 support, and cross-origin canvas elements.