The Age Discrimination in Employment Act (ADEA) is a federal law enacted in 1967 that protects individuals aged 40 and older from discrimination in the workplace. This law prohibits employers from making employment decisions based on a person's age, including hiring, firing, promotions, and compensation. The ADEA applies to businesses with 20 or more employees and covers various aspects of employment, including job advertisements and training programs. It aims to ensure that older workers have equal opportunities and are not unfairly treated due to their age, promoting a diverse and inclusive workforce.