Blending is the method of mixing different components to create something new. Everybody uses it throughout their lives without much of a thought. It can be as mundane as mixing milk and cereal or as artistic as using different pigments to create vibrant colors to express oneself. Especially in industrial applications blending can become a matter of rigorous planning. Finding the most economic recipe for a product which fulfills all requirements is often quite tricky. This is where mathematical optimization comes in. In this book, we explain the basics of using mathematical optimization to solve different kinds of blending problems. Vivid examples from the oil industry-one of oldest applications of blend optimization-are our starting point. With those we dive into different linear programming approaches, define the necessary optimization problems, and implement our examples in simple but descriptive Excel solver models. Finally, we talk about some non-linear optimization approaches, which are applied in the industry to this day, including the surprisingly unexplored field of multi-stage blending.