Alongside a revamped Gmail, Google also launched a new standalone app for Google Tasks, a web service that was previously only accessible through Gmail and Google Calendar. The app is available on Android and iOS.
Google Tasks is a task management service, where you can create tasks as reminders. You can add subtasks to existing tasks as well as additional detail. You can still add tasks the old fashioned way, through Gmail and Calendar. The app will remind you when a task is due for today.