So-called whiteboard animation - really a form of time-lapse illustration - has enjoyed a good run these last few years as an effective - and cost-effective - means of getting a message across by adding images to a explanatory narration.
When they were popularised by RSA, the standard method was to simply film someone doing a drawing on a literal whiteboard and speed up the footage. Some that I did myself involved using a large sheet of paper. This meant you could add some flexibility to the drawing style, using coloured marker pens or watercolour washes, but it also meant more rigorous preparation, limited options for amendments and having to start over if you made a mistake.
Before long, most people offering a whiteboard service shifted production to an entirely in-computer method. Most commonly, this is still done using Adobe After Effects software, whereby the entire drawing is first done, then a mask layer is painstakingly drawn over the artwork and recorded, then reversed so that the artwork is revealed as the mask is removed.
Then an image of a drawing hand is superimposed to make it look as though the artwork is being drawn 'live'.
Although keeping the entire process within the computer allows for greater production flexibility eg relatively easy alterations at any stage, and saves on overheads like studio rental and photography, it's still a slightly cumbersome method as it involves two rounds of drawing.
I now do all my whiteboard-type films using TVPaint, which enables you to record the drawing itself as you draw, not only saving the stage of retracing but allowing a much more authentic recording of that process, and a much broader variety of visual styles, few of which I have yet seen applied to the whiteboard process - which, thus far, has largely been limited to the style of an actual whiteboard.
With the personal project above, I tried to mimic the 'cigarette card' style of artwork of the early 20th century. (This film was based on a fascinating, genuine War Office document recording experiments in military flying in the moths preceding the First World War).
With this approach it's also relatively simple and economical to seamlessly add animated elements, and also to change the look of the film altogether. I made three version of this, one with line artwork only and a drawing hand added (though I feel this can actually diminish the authenticity when the artwork has all been done in-computer), and another in a 'blueprint' style. The artwork was all done in TVPaint and the final compositing in After Effects.
In the future I'd like to create a personal showreel of various illustration styles to demonstrate the broad potential of this approach, but for the moment, by way of contrast, here's a clip I did a while ago as part of a pitch for a music video project.