How many times have you thrown a penny away? Like you saw a penny on your desk, or you got it as a change, and instead of putting it in your pocket to use later, you throw it in the actual garbage? I'm not trying to judge you; I'm just trying to illustrate how the penny has lost its value over time.
In 1909, you could buy a copy of the New York Tribune for one cent. And in 1932, you could travel a mile in Southern Railway System. And I'm sure you might have heard a grandparent speak of buying candy at a local five-and-dime for a penny.
How does a penny go from getting you an entire newspaper to being so annoying that you'd rather throw them away than carry them around?
When money becomes less valuable, it's usually due to inflation.