-Weighted keys offer varying levels of resistance when pressed, depending on the pitch with heavier resistance (weight) applied to lower notes and lighter resistance to higher notes.
-They provide resistance based on the size of the hammer that they are connected to, which, in an acoustic piano, would strike the string.
-The keys of acoustic pianos are weighted due to the physical nature of how they produce sound.
-Weighted keys are also found on some digital pianos and synthesizers, providing a more authentic playing experience for pianists.