ISA/IEC 62443 is an international standard series jointly developed by the International Society of Automation (ISA) and the International Electrotechnical Commission (IEC) to address cybersecurity for industrial automation and control systems (IACS). It provides a comprehensive framework covering technical requirements, process-related aspects, and organizational measures to protect operational technology (OT) environments from cyber threats. The series is structured into multiple parts, including general concepts, policies, implementation guides, and system requirements, influencing global practices in sectors like manufacturing, energy, and critical infrastructure by promoting risk assessment, secure product development, and defense-in-depth strategies.