ICM
Independent Chip Model: converts tournament chip stacks into real dollar equity by weighing each player's finishing chances against the payouts.
ICM matters because tournament chips are not linearly valuable: doubling a stack does not double its prize-pool equity, and a min-cash is worth relatively more to a short stack than the same chips are to a monster stack. That is why ICM pressure tightens calling ranges near the bubble and at pay jumps, even as it can widen a big stack's shoving range, since the big stack risks relatively little by applying that pressure.