Shigeyuki Kondo, A Review on Enriques Surfaces: Moduli, Automorphism Groups and Positive Characteristics, I

The Enriques surface was discovered, in 1894 by Federigo Enriques, as a counter-example of a rationality problem.
First I would like to recall the moduli space and the automorphism groups of Enriques surfaces over the complex numbers.
In the later half, I shall mention a recent progress in positive characteristic, especially in characteristic two.