How exactly do regular IRAs and Roth IRAs "grow" in layman's terms?

I contribute to it and they basically invest it into whatever companies are within the plan that I select. I get that. Are those companies using it to buy stock in larger quantities and then basically "paying me back" in a sense later on when they do a little better? Is that how it grows? What about a... show more I contribute to it and they basically invest it into whatever companies are within the plan that I select. I get that. Are those companies using it to buy stock in larger quantities and then basically "paying me back" in a sense later on when they do a little better? Is that how it grows?

What about a Roth IRA? I know that the difference between a regular IRA and a Roth is that the Roth is basically guarded against future inflation, but how does the Roth grow since it isn't employer-contributed as a match? The same way?
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