the.com/checkered flag

means The black-and-white checked flag waved to signal that a race has officially finished and the leader has won.

from Its origins are genuinely murky — no one has nailed down exactly when or why the pattern became racing's finish signal. The earliest documented uses trace to American auto and bicycle races in the late 1800s/early 1900s. One popular theory ties it to county fairs, where checkered tablecloths were supposedly grabbed to signal meals were ready and horses should be brought in — but this is folk etymology, not confirmed history. More plausibly, the bold black-and-white contrast was simply chosen because it's easy to see at speed and against varied backgrounds, which is likely the real reason it stuck.