Why do dogs eat grass?

Surely you will often see different behaviors in your faithful dog that you are not very sure about.

One of these is when you see him gently chew on the grass out in your garden , and you ask yourself wheather you own a dog or a goat, you start to be worried if munching on grass might create some health problems and you catch yourself wondering why do dogs eat grass in a first place if it seems to make them vomit? Do not be alarmed, it is not as unusual behavior for dogs as you might think.