Tasks can be pretty much everything, it’s up to you. Specially when you’re working on a big task you might want to break it down into smaller, achievable goals. We call these subtasks To-dos.
To-dos are always associated to a specific task and can be marked as open or closed. Currently, tracking time against to-dos is not supported.
This is how to create a new to-do for one of your tasks:
Click on the task you want to edit. The task detail panel will appear on the right side of the screen.
Click on the information tab and on "add subtask"
You can mark to-dos are open or done anytime by ticking them using the green button. To delete a to-do erase its name and hit enter or click anywhere on the screen.
Tip: if you need to complete to-dos in a specific order you can move them around the list per Drag & Drop.