Why do we call RxJS Subject as Multicast and Observable as Unicast?

I'm going through RxJS from sometime and i can't seem to understand why do we call RxJS Subject as Multicast and Observable as Unicast.

I understood that Subject is capable of emitting data using next()and like plain Observable, we can subscribe to them as well.

I found this from RxJS official website

A Subject is like an Observable, but can multicast to many Observers.


Is this mean like a plain Observable cannot have multiple Observers?

Continue reading...