There are over 180 countries around the world with 120 kinds of money. Many designs are so interesting and pretty that some people actually collect money from different countries.

You can look at hobbyist Randy Johnson’s money collection by clicking here.

Every country has its own kind of money, usually in coins and paper. The United States has paper dollars and coins that include pennies, nickels, dimes and quarters, and less common fifty-cent and dollar coins.

Your U.S. dollar bills and coins would not be accepted if you traveled outside the United States.

For example, the Chinese, who invented paper money, use yuan. One yuan (like a U.S. dollar) is worth 10 mao (similar to the U.S. dime), and 1 mao is worth 10 fen (similar to the U.S. penny).

When you travel to China, you need yuan to buy things. How do you get yuan?

How do you know how many yuan equal one dollar? When you travel to Great Britain, you need pound sterling. How do you get pound sterling if you only have dollars or yuan?

The first thing you have to know is that the value of a dollar is not always worth the same number of yuan or pounds.

How much a currency is worth compared to another currency is called the exchange rate. The exchange rate is determined by the foreign exchange market -- when foreign exchange dealers in major cities like New York, London, Paris and Tokyo trade the money of different countries.

Another thing to know is that one day a Chinese yuan can be worth 12 cents, and the next day, only 10 cents.

When the dollar is "weak" or down against the yuan, it means one dollar is worth fewer yuans. Things will cost more in China. When the dollar is "strong" or up against the yuan, it means things in China will cost less.

Let’s imagine you are in China and buy yourself a rickshaw ride for 100 yuan. If the yuan is worth 12 cents that day, it will cost you \$12.00. If the yuan is worth 10 cents, your ride will cost \$10.00.

The Universal Currency Converter site (click here) gives you the value of the dollar against other world currencies. It can change hour by hour based on the supply and demand.

If, for example, there is a large demand for American goods and services, the dollar has a high value in comparison with the currencies of other countries.

Where can you get some yuan for your dollars when you travel to China? Most travelers use an ATM card. There are ATMs all over the world in airports, hotels and near banks and credit unions. ATM cards usually hook into a worldwide system like Cirrus or Maestro, so they can be used to get money anywhere.

You can also buy a traveler’s debit card. In that case, you put a lot of money in a special account and get a debit card just for that account. As you travel, you get the money out of ATMs, use the money up and throw away the card when your trip is over. Of course, you can also use credit cards to buy things in other countries.

You can also buy traveler's checks issued by companies like Thomas Cook or American Express. Most credit unions and banks sell them, sometimes for a fee of 1 or 2%. If these checks get lost or stolen while you’re traveling, the check company will replace them for you.

Recently, twelve European countries got together to use just one kind of money called the Euro.The Euro replaces such famous currency as the French franc, the German Deutsche mark, the Irish pound, and the Dutch guilder.

The Euro has been worth about the same amount as the American dollar, and this has made it easy for Americans to travel from country to country and buy things. Even so, there are still 35 countries in Europe that have their own currencies.

Many experts believe someday everything will be bought or sold by plastic credit or debit cards, and computers will keep track of it all. Your boss will just deposit your pay into your bank account by computer, and all your bills will be paid electronically. There will be no more paper money or coins, and we will live in a "cashless society."