This is the official manual for the latest Org-mode release.
You can use TODO keywords to indicate different sequential states in the process of working on an item, for example1:
(setq org-todo-keywords '((sequence "TODO" "FEEDBACK" "VERIFY" "|" "DONE" "DELEGATED")))
The vertical bar separates the TODO keywords (states that need action) from the DONE states (which need no further action). If you don't provide the separator bar, the last state is used as the DONE state. With this setup, the command C-c C-t will cycle an entry from TODO to FEEDBACK, then to VERIFY, and finally to DONE and DELEGATED. You may also use a numeric prefix argument to quickly select a specific state. For example C-3 C-c C-t will change the state immediately to VERIFY. Or you can use S-<left> to go backward through the sequence. If you define many keywords, you can use in-buffer completion (see Completion) or even a special one-key selection scheme (see Fast access to TODO states) to insert these words into the buffer. Changing a TODO state can be logged with a timestamp, see Tracking TODO state changes, for more information.
 Changing this variable only becomes effective after restarting Org mode in a buffer.