Whether it's baseball cards, rocks, souvenir spoons or dolls, people collect all sorts of things. In fact, collecting is one of the most popular hobbies in the world. There's virtually no limit to the kinds of things you can collect.

Why do people collect things? There are probably as many reasons for collecting things as there are things to collect. It can be a very interesting and important hobby in many ways.

For example, collections can tell stories. Just talk to any collector. There's a story behind just about every item in a collection.

It might be the collector's story — how the collector found the object, how much it cost or what it means to the collector. If it's an old object, there may be interesting stories about previous owners or what life was like years ago.

Collecting can also teach you many things. Very old objects can teach you about history and important people and events of the past.

Newer objects can teach you about current events and modern technology. Even rocks and leaves can teach you about nature and science.

So what kinds of things can kids collect? Just about anything you can think of!

What interests you? What do you like to do? Most people collect things because it extends an interest they already have.

For example, do you like sports? If so, you could collect baseball cards, autographs or other memorabilia. If you like the great outdoors, you could collect rocks, shells or fossils.

If you're a big music fan, you could collect old records, instruments or posters of your favorite musicians. If your family travels a lot, you could collect postcards, maps, souvenir spoons, license plates or even snow globes from the places you visit.

Of course, before you decide to start collecting something, you should give it a little thought. Will you be able to find items for your collection close to home?

Are the items you would like to collect expensive or free? Where will you store or display your collection?

Some objects are very expensive to collect. Fine art, jewelry, sports cars, antique furniture and rare books may be things you want to consider collecting when you have enough money to pay for them!

Expensive items are often better collected over a long period of time to reduce the cost associated with collecting them. Of course, even though these items may be expensive to collect, they can also be very valuable one day.

The late actress Elizabeth Taylor's extensive jewelry collection will be sold at auction soon, and experts believe it may be worth as much as $30 million!

Not all collections are worth a lot of money, though. For example, a personal rock collection you organize from rocks you find in the woods during hikes may not be worth much money. But that doesn't mean that it doesn't have value.

Almost all collections will have significant sentimental value to their collectors. Sentimental value is the personal value a collector places on his or her collection, based on the memories associated with the objects.

There are many free or inexpensive things you can collect that one day may have significant sentimental value to you. Some of these things could include old family letters, used stamps, shells, photographs, buttons, marbles, postcards, pins, bottles and coins.

Wonder What's Next?

Tomorrow in Wonderopolis you’ll find out why it’s sometimes a good thing to be grounded!