[en] The aim of this paper is to give an overview of the derivation and properties of exact solutions of the Einstein field equations which are spatially inhomogeneous with the source assumed to be an irrotational perfect fluid. It is shown that the known such spatially inhomogeneous solutions either admit a group of isometries with 2D orbits or are algebraically special. The solutions are related to a previously given classification scheme which is based on the intrinsic and extrinsic geometry of the hypersurfaces orthogonal to the fluid flow. (author)