Book excerpt: Structuring light is a ubiquitous laboratory tool, and computer-controlled devices such as spatial light modulators (SLMs) can reshape an input beam into almost any desired output beam. This Spotlight ranges the basic principles of these devices to some of the most advanced techniques in beam shaping. Many examples have been included to make this guide more comprehensive and help those shaping beams with a SLM for the first time. The provided examples are based in MATLAB, but they can be easily adapted to other programing languages. Readers need only an undergraduate level of mathematics and a basic knowledge of programming.