This is really nerdy.
How do you sort a bunch of numbers? Using a sorting algorithm of course! How do you understand how those algorithms work? You make visualizations!
The darker the pixel is, the higher the number is. Click on the pictures to see a larger one. You will probably have to scroll over in the larger ones.
You're allowed to ask questions if you don't understand, or if you think I need to add more explanation up here. :P
See also: sortvis.org - sorting algorithm visualisation (not mine)