Observable

• It is a wrapper around data streams or streams of values.
• Typically, usually for asynchronous data but not limited to it.
• Data streams could possibly be multiple values over time.
• Say we want to do something every time a new value comes, this is when Observer comes into play.
• Observables don’t necessarily set up the producer, they just set up an observer to listen to the producer.

Observables are lazy in the sense that they only execute values when something subscribes to it.