E-Verify is an online system that allows employers in the United States to confirm the eligibility of their employees to work. By comparing information from an employee's Form I-9, which verifies identity and employment authorization, with records from the Department of Homeland Security and the Social Security Administration, employers can ensure compliance with federal laws. The system is voluntary for most employers but mandatory for certain federal contractors and in some states. E-Verify helps reduce the hiring of unauthorized workers and supports a legal workforce, contributing to the overall integrity of the labor market in the U.S.