We have already learned a lot about building basic components and how to compose them together in order to form larger components. In the previous building block, we created a reusable checkbox UI component, which we've used to enhance the usability of our task list.

In this topic, we will use the toggle button component to create a filter for our task list. But before we start to introduce more complexity into our application, we're going to refactor our application by introducing data services. As our application gets larger, it's crucial to centralize our data manipulation and streamline our data flow. Services come in very handy since they allow us to store state which is accessible in all our components using Angular's dependency injection.

Going forward, we'll deal with quite a lot of data within our application. TypeScript supports...