Bill Clinton, the president of the United States, was impeached and then acquitted by the U.S. Senate on charges of perjury and obstruction of justice. Tony Blair was the prime minister of Britain, and the Euro currency was introduced. Amid overblown threats of cascading computer failures and widespread disaster when the new millennium began, billions of dollars were spent worldwide on Y2K computer upgrades. Meanwhile, the file-sharing service Napster quickly became popular by enabling users to share copyrighted music. Lance Armstrong won his first Tour de France, and two students opened fire at Columbine High School, killing 15 people, including themselves.