One of our assignments for class was learning about trapping. Trapping is a technique which overlaps colors where they meet to compensate for potential registration errors. Our first exercise was learning about using black vs. rich black. Black is just 100% black (key) using CMYK. This is best used to text and copy. But if you have a large space needing a lot of black (like a shape, background, etc.), it is best to use rich black. Rich black is 100% black with additional percentages of cyan, magenta, and yellow. This creates a black that is much richer and dynamic than the static black.