Plants are targets for herbivory by animals that acquire nutrients and energy from their hosts in order to grow and reproduce. Hence plants are selected to evolve resistance, which, in turn, selects for herbivores that can cope with this resistance or have the means to suppress it. Kant et al. review the current state of knowledge about plant defences and specifically emphasize insights into herbivore adaptations that allow them to cope with these defences. In addition, they provide an ecological and evolutionary perspective on the ways in which defence resistance and defence suppression by herbivores impact community interactions, and on the conditions favouring the evolution of relevant traits.