  The Erd\"os-Hajnal conjecture states that for every graph $H$, there exists a
constant $\delta(H) > 0$ such that every graph $G$ with no induced subgraph
isomorphic to $H$ has either a clique or a stable set of size at least
$|V(G)|^{\delta(H)}$. This paper is a survey of some of the known results on
this conjecture.
