An urban legend is a story that many people believe to be true. Some of these stories may have had some truth to them at one time. But they usually change over time and many are not true anymore. In the past, people read such stories in magazines and newspapers. Today, the Internet spreads them around the world much faster.

Many urban legends warn about something. One very old one is about a woman who tied up her long hair and never washed it. Spiders were said to have made a nest in her hair and killed her by eating her head. Other examples include warnings about eating two different foods or medicines at the same time, like taking an aspirin with Coca Cola.

One urban legend is about ships and planes that mysteriously disappear in an area of the Atlantic Ocean called the Bermuda Triangle. Another is about people in New York City who got rid of their small pet alligators by flushing them down the toilet. These alligators lived in New York's underground waste water system and grew to be huge. Other urban legends involve famous movie stars.

Some urban legends are false, yet are extremely difficult to stop. For example, one story said a major American company gave some of its money to the Church of Satan that worships the devil. Many people who believed this story stopped buying the company’s products even though the story was false.

Some Internet sites investigate the truth of urban legends. One is called Snopes dot com. It lists the twenty-five most popular urban legends. Many are spread through the Internet. The top one is about plastic bottles you can buy that contain water. An urban legend says that these bottles release cancer-causing substances when they are re-used. Snopes says this urban legend is false.