Due to the great importance of electrical measurements of non-electrical quantities in modern technology, there are today standardized devices and systems available for almost all measurement tasks. However, for economic reasons, there cannot be a universal measuring device for the entire range of applications, so for each measurement task, a specific measurement system must be assembled from the variety of possible measurement methods and devices. For example, in practice, specialized measurement analysis devices are used for processing the measured data rather than universal computers. Knowledge about the construction, functioning, and properties of the devices for various operating conditions is essential for making the best choice and optimal use of measurement methods and devices. This document is intended to serve both students and practitioners.