Hartvigsen, G. 2002. Predation (including parasites and disease) and herbivory. Encyclopedia of Life Sciences. Nature Publishing Group.

Organisms generally fall into two broad categories: either they are enemies or they are victims. Predation, parasitism, diseases, and herbivory all constitute ecological interactions that involve both enemies and victims. Predation is the act of an animal (enemy) capturing, killing, and consuming prey (victim). Parasites and diseases (or the agents which cause some bodily degradation) vary in their effects on victims from hardly noticeable to causing death. Finally, herbivory is that act of an animal consuming a plant. The effect of herbivory, like the effect of parasites and diseases, may be relatively minor or result in the death of the plant.