Correct and efficient measurements are vital to the understanding of materials properties and applications. This is especially so for magnetic materials for which in last twenty years, our understanding and use have changed dramatically. New or improved materials have been created and have reached the market. The Soft amorphous alloys, the Fe-based rare-earth magnets and the giant magnetorestrictive and magnetoresistive materials have all posed challenges to measurement. At the same time new digital measurement techniques have forced a change in laboratory and commercial measuring setups. A revision of measuring standards also occurred in the 1990s with the result that there is now a lack of up-to-date works on the measurement of magnetic materials. The basic objective of this work is to provide a comprehensive overview of the properties of the hard and soft magnetic materials relevant to applications and of thoroughly discussing the modern methodologies for employed in the measurement of these properties. The balance of these topics results in a complete text on the topic, which will be invaluable to researchers, students and practitioners in industry. It will be of significant interest not only to scientists working in the fields of power engineering and materials science but also to specialists in measurement who be able to easily find all the information they need.