Renormalons are smoking guns for the most important
non-perturbative effects in many quantum field theories, including
asympotically free theories like QCD. In this talk I will give an overview
of renormalons based on recent results in exactly solvable models, where
the physics and mathematics of renormalons can be studied in detail, and the corresponding non-perturbative corrections can be determined precisely. Some of these results lead also to interesting qualifications to the standard lore in renormalon phenomenology.