Freestyle swimming means...?

Question

When the US swimmer Michael Phelps became the youngest male at the time to break a world record in swimming, what was the occasion?

Answer 1

Any style for individuals, any style but breaststroke, butterfly, or backstroke for medley relays
Freestyle has come to be mostly associated with the front crawl, but technically it means any style, i.e. "free". The main features of the modern front crawl were developed in 1902 by an Englishman in Australia and it was originally called "The Australian Crawl".