A timestamp may be preceded by special keywords to facilitate planning:
Meaning: the task (most likely a TODO item, though not necessarily) is supposed to be finished on that date.
On the deadline date, the task will be listed in the agenda. In
addition, the agenda for today will carry a warning about the
approaching or missed deadline, starting
org-deadline-warning-days before the due date, and continuing
until the entry is marked DONE. An example:
*** TODO write article about the Earth for the Guide The editor in charge is [[bbdb:Ford Prefect]] DEADLINE: <2004-02-29 Sun>
Meaning: you are planning to start working on that task on the given date1.
The headline will be listed under the given date2. In addition, a reminder that the scheduled date has passed will be present in the compilation for today, until the entry is marked DONE. I.e. the task will automatically be forwarded until completed.
*** TODO Call Trillian for a date on New Years Eve. SCHEDULED: <2004-12-25 Sat>
Some tasks need to be repeated again and again. Org mode helps to organize such tasks using a so-called repeater in a DEADLINE, SCHEDULED, or plain timestamp. In the following example
** TODO Pay the rent DEADLINE: <2005-10-01 Sat +1m>
+1m is a repeater; the intended interpretation is that the task
has a deadline on <2005-10-01> and repeats itself every (one) month starting
from that time.
 This is quite different from what is normally understood by scheduling a meeting, which is done in Org-mode by just inserting a time stamp without keyword.
 It will still
be listed on that date after it has been marked DONE. If you don't like
this, set the variable