"Rerum Novarum" is an encyclical issued by Pope Leo XIII in 1891. It addresses the conditions of the working class and the rights of workers, emphasizing the importance of fair wages, safe working conditions, and the right to form unions. The document responds to the challenges posed by the Industrial Revolution and advocates for social justice. The encyclical also discusses the responsibilities of both employers and employees, promoting the idea that both should work together for the common good. It lays the foundation for modern Catholic social teaching and has influenced various social movements and policies throughout the years.