system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How exactly does a 401(k) work?
gpt
Untaxed money is taken out of your paycheck, and put into an investment account. Your employer matches what you put in up to a certain amount. That money grows tax free, and you pay taxes once you withdraw it in retirement. Very basic lowdown, a lot more info can be said.