Within an Org mode outline or outlines, headings and associated content are
treated as "flashcards".  Spaced repetition algorithms are used to conduct
interactive "drill sessions", where a selection of these flashcards is
presented to the student in random order.  The student rates his or her
recall of each item, and this information is used to schedule the item for
later revision.

Each drill session can be restricted to topics in the current buffer
(default), one or several files, all agenda files, or a subtree.  A single
topic can also be tested.

Different "card types" can be defined, which present their information to
the student in different ways.

See the file README.org for more detailed documentation.