Enriques–Kodaira classification
In mathematics, the Enriques–Kodaira classification groups compact complex surfaces into ten classes, each parametrized by a moduli space. For most of the classes the moduli spaces are well understood, but for the class of surfaces of general type the moduli spaces seem too complicated to describe explicitly, though some components are known.
Source: Wikipedia — Enriques–Kodaira classification (CC BY-SA 4.0)