Fundamentals of Analytical Chemistry are usually presented as a sum of chemical and physical foundations, laws, axioms and equations for analytical methods and procedures. In contrast, this book delivers a practice-oriented, general guiding theory valid for all methods and techniques. Starting with a closer look to analytical signals and their dependencies, all the important figures of merit characterizing the power of analytical procedures and the reliability of analytical results are discussed and quantified, such as sensitivity, precision, accuracy and ruggedness. Elements of signal theory, information theory, statistics and fundamentals of calibration are also presented for this aim. The metrological foundations included define strictly the figures of merit in order to minimize confusions still appearing in Analytical Chemistry publications today.