How does a signal notify about changes?

A signal tracks on its own who reads it. When the value changes, it notifies all the places that used it, and Angular re-renders only those areas.

In junior terms:

1. A template or computed() reads the signal via counter().
2. The signal "remembers" that these parts depend on it.
3. When set() or update() is called, the signal tells the dependent parts: "the value has changed".
4. Angular updates only them, not the whole component or application.

The signal triggers updates by itself, no manual subscriptions needed.