What a dollar (or euro, or any currency) is worth changes over time relative to other currencies which is how we can get currency trading, correct? Not only tha

What a dollar (or euro, or any currency) is worth changes over time relative to other currencies which is how we can get currency trading, correct? Not only that but a currency changes relative to itself over time. This is the purchasing power of the currency over time. Here is a calculator for that: https://www.measuringworth.com/calculators/uscompare/ https://www.measuringworth.com/calculators/uscompare/ and here: https://www.officialdata.org/us/inflation https://www.officialdata.org/us/inflation This gets called inflation. (People do argue about what inflation is and what they argue for depends on their economic ideology – there's the inflation of prices in a currency and the inflation of a currency itself through pumping more of it into the system, so-called quantitative easing) https://en.wikipedia.org/wiki/Inflation https://en.wikipedia.org/wiki/Inflation Put simple, height is measured using a fixed or absolute measure (inches or centimetres or whatever) – a $ in 1970 is not the same $ in 2020, it's relative – but we know this intuitively anyway because when we look at old prices (for most things) they are way less.