Early Career
At the age of 15, Phelps competed at the 2000 Summer Olympics in Sydney. He was the youngest American male swimmer at an Olympic Games in 68 years. While he did not win a medal, he was fifth in the 200 m Butterfly. Phelps proceeded to make a name for himself in swimming shortly thereafter. Five months after the Sydney Olympics, Phelps broke the world record in the 200 m butterfly to become, at 15 years and 9 months, the youngest man ever to set a swimming world record.[6] He then broke his own record again at the World Championships in Fukuoka, Japan (1:54.58). At the 2002 Summer Nationals in Fort Lauderdale, Phelps also broke the world record for the 400 m individual medley and set American marks in the 100 m butterfly and the 200 m individual medley.

In 2003, Phelps broke his own world record in the 400 m individual medley (4:09.09) and in June, he broke the world record in the 200 m individual medley (1:56.04). Then on July 7, 2004, Phelps broke his own world record again in the 400 m individual medley (4:08.41) during the U.S. trials for the 2004 Summer Olympics.

Phelps' dominance has brought comparisons to former swimming great Mark Spitz,who won seven gold medals in the 1972 Summer Olympics, a world record. Phelps tied Mark Spitz's record of four gold medals won in single person events. Phelps had the chance to break Spitz's record of 7 total gold medals in the 2004 Athens Olympics by competing in eight swimming events (5 of which were individual events): the 200 m freestyle, the 100 m butterfly, the 200 m butterfly, the 200 m individual medley, the 400 m individual medley, the 4x100 m freestyle relay, 4x200 m freestyle relay, and the 4x100 m medley relay. However, his 4x100 m freestyle relay team only won the bronze medal, and he personally placed for bronze in the 200 m freestyle. Thus, he fell short of that record. However, he did win eight medals in one Olympics, a feat only achieved by Alexander Dityatin, a gymnast, in the 1980 Olympics in Moscow.

Had he won seven golds, he would have been eligible for a US$1 million bonus from his sponsor, Speedo.
Phelps does, however, have another chance at this $1 million should he win seven or more golds at the 2008 Olympic Games in Beijing.

On August 14, 2004, he won his first Olympic gold, in the 400 m individual medley, setting another new world record (4:08.26). On August 16 he was beaten by the Australian winner Ian Thorpe and the Dutch Pieter van den Hoogenband in 200 m freestyle final, called the race of the century.

On August 20, in the 100 m butterfly final, Phelps defeated American teammate Ian Crocker (who holds the world record in the event) by just 0.04 seconds. Traditionally, the Olympian who places highest in an individual event will be automatically given the corresponding leg of the 4x100 m medley relay. This gave Phelps an automatic entry into the medley relay but he deferred and Crocker swam instead. The American medley team went on to win the event in world record time, and, since he had raced in a preliminary heat of the medley relay, Phelps was also awarded a gold medal along with the team members that competed in the final.

Phelps grew up in the Rodgers Forge neighborhood of Baltimore, Maryland, and graduated from Towson High School in 2003. His father, Fred Phelps, worked with the Maryland State Police and his mother, Debbie Davisson Phelps, has worked as a school teacher and administrator. The two divorced in 1994. Michael has two older sisters, Whitney and Hilary. Both of them were swimmers as well, with Whitney coming close to making the U.S. Team for the 1996 Summer Olympics before injuries derailed her career.

In his youth, Michael was diagnosed with Attention-Deficit Hyperactivity Disorder (ADHD). He started swimming at age seven, partly because of the influence of his sisters and partly to provide him with an outlet for his restless energy. He blossomed quickly as a swimmer, and by the age of 10 held a national record for his age group. More age group records followed, and Michael's rapid improvement culminated in his qualifying for the 2000 Summer Olympics at the age of 15.

In November 2004, Phelps was arrested for drunken driving in Salisbury, Maryland. He pled guilty the following month and was granted probation before judgment and ordered to serve 18 months probation.[11] As of 2007, Phelps is now attending the University of Michigan in Ann Arbor, Michigan, intending to major in sports marketing or sports management. Phelps followed his longtime coach, Bob Bowman to Ann Arbor. Bowman left Phelps' previous swim team, the North Baltimore Aquatic Club, to become the head coach of the University of Michigan varsity swim team. Phelps is serving as a volunteer assistant coach, but cannot swim for the university's team because of his loss of amateur status. Phelps is sponsored by Speedo, Visa, Omega, PowerBar, and Matsunichi.

Phelps, along with Ian Crocker and Lenny Krayzelburg, founded the "Swim with the Stars" program. This program promotes swimming and conducts camps for swimmers of all ages.