All Dart projects that are meant to be used in a production environment should follow best software engineering practices and hence, must contain a particular structure of folders. A well-structured project breathes professionalism and gives developers a sense of recognition; it is much easier to find your way in a standardized structure. Moreover, it is also necessary if you want to use a bunch of application-specific libraries in your app, as we will see in the next recipe.
An app that is meant to run on its own, either as a command-line application or a web application, is an application package; it needs a main() entry point. A library package will be used as a dependency in other apps. All Dart projects depend on the configuration file pubspec.yaml, which describes the app and its dependencies, together with the pubspec.lock file. This dictates which libraries will be contained in the top-level packages folder. This file and the packages folder...