A billionaire is a person who has a net worth of at least one billion dollars. That's $1,000,000,000: a thousand million dollars, or enough money to buy a thousand houses worth a million dollars each. To put it another way, if you spent $1,000 every single day, it would take you nearly 3,000 years to spend a billion dollars.

Most billionaires became wealthy by building successful companies. Jeff Bezos founded Amazon, an online shopping company. Oprah Winfrey built a media empire through television, publishing, and other businesses. Some billionaires, like Warren Buffett, made their fortunes by investing wisely in other people's companies. A few inherited their wealth from family members who built successful businesses.

The word combines billion with the suffix -aire, which comes from French and means “a person who has.” A millionaire has at least a million dollars, while a billionaire has a thousand times more than that.

There are only a few thousand billionaires in the entire world. Their immense wealth gives them the power to influence entire industries, fund scientific research, support charitable causes, or shape public opinion. Some use their wealth generously to help others; some focus mainly on making more money; many do both. The choices billionaires make with their resources can affect millions of people's lives, which is why their decisions often make headlines.