Answer:
Representing workers in negotiations with employers, labor unions have been in existence for centuries. They negotiate for better wages, benefits, and safer working conditions. In the late 19th and early 20th centuries, they became more prevalent in the United States due to workers' growing dissatisfaction with their working conditions. Labor unions have helped to improve these conditions by negotiating for higher pay, shorter hours, and safer work environments. Additionally, labor unions have played a crucial role in protecting workers' rights by fighting against discrimination and unfair labor practices, especially in the early 20th century when many workers were fired for trying to organize a union or speaking up about their working conditions.