A UI component consists, as you can see, of several parts that interact with each other. When a user interacts with the UI by clicking a button, some logic triggers inside the component. Depending on the logic, several things can happen within the component. The internal state of the component gets updated, we send a request to the back end, or we provide information back to the user. One important path inside the component is missing though. Through its API, it can provide information to other components. This only works when other components connect to your component, by providing a callback function (e.g. an onClick function for a button component).