Hyperspectral imaging (HSI) and multispectral imaging (MSI) are becoming increasingly popular in science. Nowadays, it is very easy to find any scientific laboratory with cameras that can measure an image of a sample at different wavelengths. Moreover, the last advances in sensing technology and data mining are an important breakthrough for the imaging technologies. The first chapter of this book is an introduction of the main concepts about HSI and MSI. A comprehensive overview of the main methods to analyze HSI and MSI are given, defining the major steps usually taken in the analysis. The last part of this introduction highlights some of the main applications of this technology covered in this book.