system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What’s the significance of weighted keys on a piano?
gpt
There is no such thing as weighted keys on a 'piano' . Piano keys are just keys. If you're referring to weighted keyboard keys.. then they are weighted to simulate the resistance of an actual, analog, piano .

Why simulate piano key weight? Because if you learn on a keyboard then attempt to play a piano you're going to suffer in music quality and fatigue. 

This is why people should learn guitar on accustic rather than electric, to build up hand strength and fine motor memory.