Unlike hands, feet are common among more animals, although they do vary signifcantly among each animal. Most vertebrates (animals that have backbones) have feet that are located at the end of each of their legs. Generally the foot is a complex structure that is made up primarily of bone, muscle and connective tissue. At one point in our lives I'm sure we have seen our feet, or the feet of our household pets which are called paws. Animals feet are called paws because they have soft or padded feet.
This varies differently from mollusks (soft bodied, shelled animals such as clams & oysters) that have a primarily muscular foot structure. Humans use their feet for something that is almost unique to them which is bipedal locomotion. We never put much thought into it, but it's a very special ability that we have, and is known as walking. Although both our feet and hands have the same five digit anatomy, the foot is lacking the opposable thumb and the dexterity that we enjoy from our hands. Although the feet are a relatively small section of our body, they comprise of half the bones in our body and are very intricate in structure.
The foot design is so intricate because of the amount of weight that is placed on the foot among other tasks such as balancing. There is a huge list of foot problems that can be experienced from improper loading,etc of the foot, a few of which I have listed: Heel Spurs, Achilles Tendonitis, Plantar Fasciitis, Arch/Pain Strain, Shin Splints, Arthritis. For the most case all of these conditions are preventable and can be treated by a foot doctor. If you are experiencing any pains or other symptoms in your feet and lower legs it is recommended to have it looked at as soon as possible, as our feet provide us with a strong foundation for live; no kidding.