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:
Rotate the TODO state of the current item among
(unmarked) -> TODO -> DONE -> (unmarked)
The same rotation can also be done “remotely” from the agenda buffers with the t command key (see Agenda commands).
Select the following/preceding TODO state, similar to cycling.
View TODO items in a sparse tree (see Sparse trees). Folds the buffer, but shows all TODO items and the headings hierarchy above them.
Show the global TODO list. Collects the TODO items from all agenda files (see Agenda Views) into a single buffer. See Global TODO list, for more information.
Insert a new TODO entry below the current one.
Changing a TODO state can also trigger tag changes. See the docstring of the
org-todo-state-tags-triggers for details.