Topology of Algebraic Varieties

The Andre-Oort conjecture describes the expected distribution of special points on Shimura varieties (typically: the distribution in the moduli space of principally polarized Abelian varieties of points corresponding to Abelian varieties with complex multiplication). From the point of view of Hodge theory, it completely describes the geometric properties of the Hodge locus in some special instances. In these lectures I will try to introduce Shimura varieties, the Andre-Oort conjecture and recent work on it.