Why does my dog (or cat) eat grass?

One of my cats loves to eat grass. Then again, he loves to eat everything he can! Why do pets eat grass? It may be normal, some pets seem to like the taste of grass. They not be feeling well and eat grass to vomit. Or they may vomit after eating grass. There are many theories about pets and grass, but if your pet exhibits an odd appetite (eating non-food items regularly, called pica), or regular vomiting, please contact your vet as soon as possible.