Subtask functionality
If you have a task then to complete that you have to perform some kind of subtasks too. You can simply create subtasks within tasks and assign them to anyone in your team. You can have a detailed view of the subtask in overview with many options. So, to perform a subtask you can change the status of your subtask. When your all subtasks are completed then you can change task status to Done.
Notification functionality
You can see different types of notifications arrive to you in the header section. Just click the bell icon and you can see notifications. You can click on any specific notification and view its detailed view.