Simple irreducible subgroups of exceptional algebraic groups

A closed subgroup of a semisimple algebraic group is called irreducible if it lies in no proper parabolic subgroup. In this paper we classify all irreducible subgroups of exceptional algebraic groups G which are connected, closed and simple of rank at least 2. Consequences are given concerning the representations of such subgroups on various G-modules: for example, with one exception, the conjugacy classes of irreducible simple connected subgroups of rank at least 2 are determined by their composition factors on the adjoint module of G.