 This paper provides a comprehensive review of optically pumped magnetometers, OPMs, based on alkali atomic vapour cells. It begins with a discussion of the atomic magneto-optical effect, which is used in these devices. The paper then examines the performance of OPMs compared to other types of magnetometers, such as squids and superconducting quantum interference devices, squids. It also explores the effects of various noise sources on magnetometer performance. The paper concludes with a comparison of different OPM designs and a summary of current research into this technology. Additionally, it offers practical advice for implementing OPMs, including a discussion of the design process for a particular magnetometer called the M-Underscore Z magnetometer. Finally, a workbook containing real magnetometer data is included to demonstrate the analysis of magnetometer performance. This article was offered by Enfabrikant, Irina Novikova and George Bison. We are article.tv, links in the description below.