Epic is the dominant electronic health record (EHR) system in US healthcare, managing patient records, clinical workflows, billing, pharmacy, lab, imaging, and scheduling across hospitals and health systems. It integrates all aspects of healthcare operations—provider notes, lab results, medications, billing codes, insurance verification. Practitioners configure Epic to match hospital workflows, integrate with other systems (LAB information systems, pharmacy systems, imaging archives), and ensure clinical safety (medication errors are lethal). It's mission-critical infrastructure.