Niklas Luhmann was a German sociologist known for his development of systems theory. He proposed that society is made up of complex systems that operate independently but are interconnected. His work emphasized the importance of communication in social systems, suggesting that social interactions create and maintain these systems. Luhmann's theories challenged traditional views of sociology by focusing on the processes and structures that shape social life rather than individual actions. He wrote extensively, with notable works including Social Systems and The Society of Society, which explore how systems evolve and adapt over time through communication and observation.