5.3.1 Closing items

The most basic automatic logging is to keep track of when a certain TODO item was marked as done. This can be achieved with⁴¹

(setq org-log-done 'time)

Then each time you turn an entry from a TODO (not-done) state into any of the DONE states, a line ‘CLOSED: [timestamp]’ is inserted just after the headline. If you turn the entry back into a TODO item through further state cycling, that line is removed again. If you turn the entry back to a non-TODO state (by pressing C-c C-t SPC for example), that line is also removed, unless you set org-closed-keep-when-no-todo to non-nil. If you want to record a note along with the timestamp, use⁴²

(setq org-log-done 'note)

You are then prompted for a note, and that note is stored below the entry with a ‘Closing Note’ heading.