Represent each number as a row of beads on an abacus. Let gravity pull beads down. After settling, reading rows bottom-to-top gives the sorted array. Like a physical sorting machine!
Worst: O(n × max_val)
Average: O(S) where S = sum
Best: O(1) with hardware
Space: O(n × max_val)
Only works for positive integers. Beautiful but impractical without hardware.