The purpose of these notes is to give a self-containing introduction
to big Witt vectors and the big de Rham-Witt complex. This complex,
introduced by Madsen and myself, is defined for every commutative ring
and generalizes the classical p-typical de Rham-Witt complex
of Bloch, Deligne, and Illusie.
A new and much better construction of the big de Rham-Witt complex is
given in the later paper "The big de Rham-Witt complex."