# lifecycle library | |
*[<Null safety>](https://dart.dev/null-safety)* | |
<p>The lifecycle interface defines a service which allows running components | |
to be notified when lifecycle events happen in the system.</p> | |
## Classes | |
##### [Lifecycle](../package-fuchsia_modular_lifecycle/Lifecycle-class.md) | |
Allows running components to be notified when lifecycle events happen in the | |
system. | |