Automorphisms of finite order and real forms of "smooth" affine Kac-Moody
algebras are studied, i.e. of 2-dimensional extensions of the algebra of smooth
loops in a simple Lie algebra. It is shown that they can be parametrized by
certain invariants and that in particular the classification of involutions
essentially follows from Cartan's classifications in finite dimensions. We also
prove that our approach works equally well in the usual algebraic setting and
leads to the same results there