Planner is a light weight, mobile and web-based application where you can create plans, assign tasks, chat about tasks, and see charts of your team's progress.
You can learn more about Planner from the Microsoft Planner Documentation website.
Note: A Microsoft Planner plan can only be created if you are an owner or member of a Microsoft Team. Click here to learn more and request a Microsoft Team.
Click here to access Microsoft Planner