Michael Phelps first Olympic appearance came in 2000 in Sydney when he was chosen for the US swim team at the age of just 15 - the youngest American swimmer selected for a Games in almost 70 years.

He failed to win a medal in Australia but it was clear that Sydney was just a learning experience and this was to prove no setback. A year later Phelps became the youngest male swimmer to break a world record with a win in the 400m freestyle at the 2001 World Aquatics Championship - a taste of future glory.

At the 2004 Olympic Games in Greece, Phelps did not disappoint. In his first event, the 400-meter individual medley, he won with a world record time of 4:08.26 to take his first Olympic gold medal.

Though he lost out to Ian Thorpe in the 200m freestyle, the so-called "Race of the Century", the following days saw the young American scoop gold in the 200m butterfly, the 4x200 freestyle relay, the 100m butterfly and the 4x100m medley. Six gold and two bronze medals meant Phelps had achieved the second-best performance at an Olympics Games - he was second only to the legendary swimmer of 1972, Mark Spitz.

Come Beijing in 2008, following four years in which he won 17 World Championship gold medals, Phelps broke Spitz's long-standing record. He won his eighth Olympic gold medal in the 4x100m medley relay - setting a new world record for good measure - with a little inspiration from Australian rival Ian Thorpe, who earlier declared such an achievement impossible. Phelps took note and stuck Thorpe's statement on his locker.

By the time London 2012 came round Phelps was, like Usain Bolt, a global star - a brand in his own right - and had even set up a foundation in his own name to promote healthy living and fitness for children. Having earlier announced his retirement, the world waited with bated breath to see if The Flying Fish could become the most decorated Olympian of all time.

Despite some shocks at the Aquatics Centre - coming fourth in the 4x100m individual medley behind rising star Ryan Lochte and finishing second to Chad Le Clos of South Africa in the 200m butterfly - Phelps duly obliged.

A gold medal in the 4x200m freestyle relay, added to his 200m butterfly silver earlier that day, meant he had now surpassed Soviet-era gymnast Larisa Latynina's record of 18 Olympic medals.

He went on to win his fifth 200m individual medley gold - a competition record - and secure another first in what he said was his last-ever individual race, the 200m butterfly. Phelps rounded off his career in style as part of the winning USA team in the 4x100m medley relay, in front of an ecstatic crowd.

It's not clear what the Michael Phelps way will be from this point on, but with 22 Games medals to his name, including an astonishing 18 golds, his record as the most decorated Olympian of all time seems likely to last for at least the rest of his retirement.

Follow some of the best of Michael Phelps' Olympic moments in this playlist! less