In Angular v16, signals were introduced as a new reactive primitive to enhance state management and streamline change detection. Signals are functions that hold a value and emit updates when that value changes, enabling fine-grained reactivity without relying on manual subscriptions or complex observables.

With this solid foundation layed out with signal(), computed() and effect, additional primitives we're introduced in the following minor/major versions.

Amongst other we have today:

• input(), for inputs
• Signal Queries (viewChild(), viewChildren, contentChild(), contentChildren())
• model() for double binding
• linkedSignal
• resource/rxResource
• afterRenderEffec()

Each of those primitives provided by the framework addresses specific usecases. It can become difficult to determine which is the exact tool you are looking for.

Here is a chart that might help you determine what is the tool that your are looking for.

As you can see, this chart assumes that you already know when to reach out for Signals and when/what observable is better suited.

Note: I'll try to keep this chart up-to-date with new primitives that might be around the corner or when new use cases arrise.