Each square represents an album, with sampled artists on the lower half and sampling artists on the upper half. Albums are placed horizontally according to release date, while vertical placement reflects the number of samples on that album. The middle resprents the area of most sampling, so commonly sampled albums are closer to the side with the sampling albums, and vice versa.
The rectangles that appear to the right of a selected album represent the individual songs. Songs with taller rectangles have a higher sample count.
The sampling data is from the-breaks.com, although album information for the sampling songs was collected through other means.