The efficient solution of many important problems in applied geometry relies on the use of effective mathematical and computational tools. This book presents, using a light approach, a sampler of tools that have been adopted in computer graphics, image processing, vision, and geometry in general. The focus is on computational and algorithmic details, without delving too deeply into the underlying theoretical analysis. The book covers a wide range of topics, from matrix decomposition to curvature analysis, and principle component analysis to least square fitting, to name a few.