Without redefining, let's look at the description of @ngrx/effects straight from the repo (https://github.com/ngrx/effects):
In @ngrx/effects, effects are the sources of actions. You use the @Effect() decorator to hint which observables on a service are action sources, and @ngrx/effects automatically merges your action streams, letting you subscribe them to store.
To help you compose new action sources, @ngrx/effects exports an action observable service that emits every action dispatched in your application.
In other words, we can chain our actions together with effects to provide powerful data flow composition throughout our app. They allow us to insert behavior that should take place between when ...