Now that spring is here, you've probably started thinking about going barefoot. Your feet have been hidden away in shoes or boots all winter. But now that it's April, you may already be running around your house without any shoes on. Have you taken a close look at your feet?

Feel your feet with your hands. You'll find a complicated set of bones -- 26 separate bones in each foot. That's about one quarter of all the bones in your body.

Your feet are moveable because 33 joints in each one allow you to change the positions of the bones. Flexible bands of tissue stretched between the bones hold all this complicated body machinery together. These bands are called ligaments. Each one of your feet has 100 ligaments.

The skin on your feet is specially designed to take a lot of pressure, too. The bottoms of your feet have thicker skin than the rest of your body does. Your toenails provide protection, too. Imagine what it would be like to wear shoes if you didn't have any toenails.

But all the complicated stuff in your feet can cause trouble. Some experts say that foot problems are the most common ailment Americans have -- after colds and tooth decay. That's not very surprising when you think about the job your feet have to do.

All your life, your feet carry you around. They must balance and support your entire body. Your feet cushion your weight when you run or jump -- often on hard pavement, which doesn't give when you land on it the way earth or sand does. One day's worth of walking puts a lot of total weight on your feet -- an amount equal to a few hundred tons by the time you finally go to bed at night.

When you were a baby, the bones in your feet were still soft. Because of this, doctors think that babies are better off without shoes until they begin to walk. Then, they start wearing shoes. When your parents got you your first pair of shoes, they were careful to see that the shoes allowed room for growth. New shoes for young children should have a thumb-width of space between the end of the longest toe and the end of the shoe.

Eliezer Trybuch is a podiatrist, or foot doctor. He sees many children with foot problems in his office every year. Trybuch says that kids often don't complain if their shoes hurt. But they should. If your shoes feel wrong, tell your parents. You may need a new pair, or a different style. Your parents can look at the shoes and see if they are wearing down unevenly.

Trybuch says this is why you have so many bones in your feet:

A long, long time ago, human beings' ancestors used their feet to grasp things with just as we can use our hands. As time went on, these monkey-like ancestors of humans started to walk on their feet. "The bones designed for grasping stayed the same, but the muscles around the feet changed," Trybuch says.

The muscles in your feet aren't as complicated as those in your hands, although they work in similar ways. The feet are still bendable -- but not as much as the hands. You might be able to hold a pencil with your toes, but you'd have a hard time writing a letter that way -- although some people have trained themselves to do that.

You have probably noticed that your "baby" toes are pretty small. Do they have a job to do?

Trybuch says: "You use your baby toe for balancing. But we know that as time goes on, people's little toes are getting littler and littler." In many years, he says, little toes may disappear completely, because people can balance well enough without them.

Your big toe, however, has a very important job. It helps you walk.

Each time you take a step, it's like losing your balance, falling forward and then catching yourself with your foot. "When we push our weight forward we push off with our big toe," Trybuch says. "It has a bigger, thicker bone than the other toes. There are some muscles that attach only to the big toe. It helps you push off, balance and keep moving forward."

What's a good exercise for your feet? Try walking on the beach barefoot. "Sand is soft and fits to the shape of your foot," Trybuch says. "You use all your muscles."

But don't try it on the street, he adds.

"Don't walk barefoot where's there's glass and other stuff that could hurt you. Your feet weren't designed to walk barefoot on concrete. You need shoes. In this weather, sandals or sneakers are good. They allow the feet to sweat freely. And that feels good after having your feet cooped up in leather shoes all winter." Tips for Parents

"Kids will tolerate a lot of discomfort without saying anything," says Eiezer Trybuch, a District podiatrist. "Watch the way your kids walk. If they start looking pigeon-toed, they may be walking that way to take pressure from the shoes off their toes."

Trybuch suggests these tips for adult and child foot care:

* Always dry the feet well after washing -- especially between the toes.

* Cut toenails straight across.

* Don't use harsh "home cures" for ingrown toenails. The acid they contain can damage tissues.

* Avoid tapered shoes that press on the toenails. Don't wear street shoes for sports.

* Try on shoes when standing up with the whole weight of the foot in the shoe.

* Walk as much as you can.