This class focuses on understanding the measurements made in passive seismic. I explain principles of microseismic monitoring ranging from acquisition in a single monitoring borehole to surface and near surface networks with DAS or point sensors to engineering applications of microseismicity. The case studies are used when they illustrate the conceptual point and the practical impacts on microseismic monitoring. At the end of this class, attendees should be able to design and select a monitoring array and processing workflow that meet their specific objectives. They will learn how to recognize and avoid misinterpretation of uncertain observations and gain insight into the reliable information provided by microseismicity. No prior course is required, although knowledge of hydraulic fracturing and seismology is beneficial. The course will also cover the latest developments in microseismic applications, including DAS acquisition, source mechanisms, anisotropy, and engineering applications.