Book excerpt: One of the most important aspects for a successful police operation is the ability for the police to obtain timely, reliable and actionable intelligence related to the investigation or incident at hand. Open Source Intelligence (OSINT) provides an invaluable avenue to access and collect such information in addition to traditional investigative techniques and information sources. This book offers an authoritative and accessible guide on how to conduct Open Source Intelligence investigations from data collection to analysis to the design and vetting of OSINT tools. In its pages the reader will find a comprehensive view into the newest methods for OSINT analytics and visualizations in combination with real-life case studies to showcase the application as well as the challenges of OSINT investigations across domains. Examples of OSINT range from information posted on social media as one of the most openly available means of accessing and gathering Open Source Intelligence to location data, OSINT obtained from the darkweb to combinations of OSINT with real-time analytical capabilities and closed sources. In addition it provides guidance on legal and ethical considerations making it relevant reading for practitioners as well as academics and students with a view to obtain thorough, first-hand knowledge from serving experts in the field.