What is Observer?

The term "Observer" is quite generic and, without more context, could refer to several different technologies or concepts. It often relates to the Observer pattern in software design, a behavioral design pattern where an object, named the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods. This is commonly used to implement distributed event handling systems. It can also refer to tools or systems used to monitor and analyze data or events in various domains, such as network monitoring tools or systems for observing user behavior.