An Observable is basically a function that can return a stream of values either synchronously or asynchronously to an observer over time. The consumer can get the value by calling subscribe() method. Let's look at a simple example of an Observable
import { Observable } from 'rxjs';
const observable = new Observable(observer => {
setTimeout(() => {
observer.next('Message from a Observable!');
}, 3000);
});
observable.subscribe(value => console.log(value));