Concept of the day1 / 3
Error-correcting codes
The conceptWhy a scratched DVD still plays perfectly
A scratched disc still plays without a skip because it stores more than the song: extra numbers computed from that same data, used to spot and fix damage.
Those extra numbers are called error-correcting codes. If a few bits go missing or get flipped, the player treats it like a sudoku puzzle: enough of the picture is still there to work out exactly what the missing pieces must have been.