When talking about Observables, we use terms such as emit/send value/item. Commonly, we say that an Observable emits an item, but we understand the same from an Observable sends a value as well.
By emit/send we mean that an Observable is calling the onNext method on an observer.
When talking about Observables, we use terms such as send error/complete notification/signal. We also often mention that an Observable completes, which means that an Observable has sent a complete notification.
By notification/signal we mean that an Observable is calling the onError or onComplete method on an observer.
In the preceding paragraph, we worked with a simple RxPHP demo that had one Observable, two operators and one observer.
This structure formed an operator/Observable chain. We'll understand the same thing from both of the terms operator chain and Observable chain (sometimes also referred to as a chain of Observable operators). This is because, from our perspective...