Omnivores are animals that eat both meat and plants. Some omnivores, like bears, hunt and forage for their food. Other omnivores are scavengers and eat dead matter left over from other predators. Many omnivores eat the eggs from other animals.
Omnivorous animals are believed to be this way out of need for survival. Being omnivorous opens up more opportunity to find food (they can eat all of the things herbivores can eat as well as all of the things that carnivores can eat). You can identify an omnivorous animal by the shape of their teeth. They will have a combination of sharp teeth (for tearing meat), flat teeth (for cutting leaves, grains), and flat, molar-like teeth (for bringing down food).