  We describe a simplified categorical approach to Galois descent theory. It is
well known that Galois descent is a special case of Grothendieck descent, and
that under mild additional conditions the category of Grothendieck descent data
coincides with the Eilenberg-Moore category of algebras over a suitable monad.
This also suggests using monads directly, and our monadic approach to Galois
descent makes no reference to Grothendieck descent theory at all. In order to
make Galois descent constructions perfectly clear, we also describe their
connections with some other related constructions of categorical algebra, and
make various explicit calculations, especially with 1-cocycles and
1-dimensional non-abelian cohomology, usually omitted in the literature.
