Could you explain what an Observable object is in the context of reactive programming?

Observable is a key object in reactive programming that represents a stream of data or events that can be subscribed to. It allows asynchronous data reception as they occur, processing them and reacting to changes.

An Observable can emit three types of notifications:

• Next — a new value in the stream
• Error — an error that interrupts the stream
• Complete — a signal that data transmission has finished

For example, in Android with RxJava, you can create an Observable that emits values based on a timer or an event, and a subscriber will process these values.