  A brief review of the theoretical description of exclusive and inclusive
semileptonic charm decays is given. In light of the recent experimental puzzles
in leptonic charm decays, the complementary role of semileptonic modes is
emphasized. The relevance of semileptonic charm decay studies to the precise
determination of the Vub CKM matrix element from semileptonic B decays is also
discussed. Some interesting and important theoretical challenges are mentioned.
