Can Tasks be Nested beneath other Tasks to have Sub-Levels/Sub-Groupings?

Can Tasks be Nested beneath other Tasks to have Sub-Levels/Sub-Groupings?

I like the existing feature that one can have sub-tasks within a task.  

Yet, can we group Tasks under other Tasks or Groups - such as nesting via sub-levels - to help us organize & prioritize a long-growing list of Tasks?

Thanks in advance... :)  Jason