Anti-Ghosting
Prevents specific key combinations from registering incorrectly (a common issue when multiple keys are pressed simultaneously on lower-cost keyboard matrices), typically covering a defined set of common gaming key combinations.
N-Key Rollover (NKRO)
Goes further, guaranteeing every key can register correctly regardless of how many others are held down simultaneously — the more complete and more expensive-to-implement solution, standard on competitive-tier gaming keyboards.