E.g. Select “Watch a Movie” and the TV comes on the right channel, the movie server switches on, the blinds close and the lights dim. So the TV “talks” to movie server, the motor on the blinds and the electrical light circuit. Clever.
E.g. You open your electrcic gates when arriving home and the external drive and door lights come on, as to does the entry security camera
The wiring we use to make these systems talk to each other is called KNX. Most Manufacturers have KNX gateway so their devices can sit on a KNX network