Any headline becomes a TODO item when it starts with the word ‘TODO’, for example:
*** TODO Write letter to Sam Fortune
The most important commands to work with TODO entries are:
,-> (unmarked) -> TODO -> DONE --.
'--------------------------------'
The same rotation can also be done “remotely” from the timeline and
agenda buffers with the t command key (see Agenda commands).
Changing a TODO state can also trigger tag changes. See the docstring of the
option org-todo-state-tags-triggers for details.