When you subscribe() to an Observable to receive emissions, a stream is created to process these emissions through the Observable chain. Of course, this uses resources. When we are done, we want to dispose of these resources so that they can be garbage-collected. Thankfully, the finite Observables that call onComplete() will typically dispose of themselves safely when they are done. But if you are working with infinite or long-running Observables, you likely will run into situations where you want to explicitly stop the emissions and dispose of everything associated with that subscription. As a matter of fact, you cannot trust the garbage collector to take care of active subscriptions that you no longer need, and explicit disposal is necessary in order to prevent memory leaks.
The Disposable is a link between an Observable and an active Observer,...