Venom is a general term for the toxins used by several groups of animal species for the purpose of defense and hunting prey. Most widely known are snakes, some species of which inject venom into their prey through hollow fangs, spiderss, which also inject venom through "fangs", and stinging insects, who inject venom with a sting. Wasps and bees illustrate the two divisions in the definition above. Bees use a venom designed to cause pain to the stung, because their purpose is to defend their home and food stores, while wasps use a chemically different venom designed to paralyze the prey, so it can be stored alive in the food chambers of their young. The use of venom is much more widespread than just these examples, of course.
Antivenom (or antivenin) is used in the treatment of venomous bites. It is created by injecting a small amount of the targeted venom into an animal such as a horse, a goat, or a rabbit; the subject animal will suffer an immune response to the venom, producing antibodies against the venom's active molecule which can then be harvested from the animal's blood and used to treat envenomation in others.
See also: poison.
Venom also has these other meanings: