Quest Diagnostics is a clinical laboratory testing and diagnostic information services company that operates primarily through its Diagnostic Information Services segment, which provides laboratory testing, diagnostic insights, and actionable health information to physicians, hospitals, health plans, employers, and patients. The company generates revenue from four primary customer groups—healthcare insurers, government payers, healthcare providers and employers, and patients—collecting fees for laboratory tests completed through its network of patient service centers, laboratory facilities, phlebotomists, and call centers. The business derives value from one of the world's largest databases of de-identifiable clinical lab results, which it leverages to deliver diagnostic and analytical insights that help identify and treat disease while supporting broader healthcare management and improvement efforts.