Observers are individuals or devices that watch and record events or phenomena. They play a crucial role in various fields, such as science, astronomy, and social research. For example, in astronomy, telescopes are used as observers to study celestial bodies, while in social research, people may observe behaviors in a community to gather data. In many cases, observers can be categorized as either passive or active. Passive observers simply watch without interfering, while active observers may engage with the subject or environment. Both types provide valuable insights, helping to enhance our understanding of the world around us.