External Attack Surface Management (EASM) has emerged as a significant focus within the cybersecurity industry, driven by the increasing complexity and expansion of attack surfaces, which Gartner identified as the top cybersecurity risk in 2022. EASM is a subset of the broader Attack Surface Management (ASM) framework, which involves the continuous monitoring and assessment of IT assets to identify exposures, with EASM specifically targeting the discovery and analysis of unknown internet-facing assets. Despite its growing relevance, many users are still unclear about EASM's role and its integration into existing security workflows. The e-book titled "External Attack Surface Management (EASM): What it is and what it isn’t" aims to clarify EASM's definition, its relationship with other ASM categories such as Cyber Asset Attack Surface Management (CAASM) and Digital Risk Protection Service (DRPS), and how security teams can utilize EASM to address critical questions about asset vulnerabilities, focus areas, and remediation strategies.