  The study of affine Deligne-Lusztig varieties originally arose from
arithmetic geometry, but many problems on affine Deligne-Lusztig varieties are
purely Lie-theoretic in nature. This survey deals with recent progress on
several important problems on affine Deligne-Lusztig varieties. The emphasis is
on the Lie-theoretic aspect, while some connections and applications to
arithmetic geometry will also be mentioned.
