These were the first Olympic Games in which a 100-metre pool had been especially constructed (inside the main stadium's track and field oval).

Previous Olympic events were swum in open water (1896: The Mediterranean Sea, 1900: The Seine River, 1904: an artificial lake).

[citation needed] This was the third appearance of the men's 100 metre freestyle (including the 100 yard event in 1904 but excluding the Intercalated Games in 1906).

[citation needed] Australasia, Belgium, Canada, Denmark, France, Great Britain, Italy, the Netherlands, and Sweden each made their debut in the event.

Hungary and the United States each made their third appearance, having competed at each edition of the event to date.

[citation needed] With a much larger field than in 1904, the 1908 competition expanded to three rounds: heats, semifinals, and a final.

The 1908 Games also restored the wild-card system from 1900, allowing the fastest swimmers who did not win their heat to advance.