It depends whether they ask it in casual or serious manner. At bare minimum, i would say
1. Cryptocurrency is a kind of digital money/currency that isn't controlled by government.
2. Just like fiat, you can make money on cryptocurrency by doing a job.
Exactly, it's a great summary to talk about quickly
For some friends, that's enough for them to move on to the next subject, but when the person becomes more interested and starts to ask how it is, where the coins comes from, how to trust it, etc., then I try to give a few more explanations
Analogies are still the best way to explain
For some, I explain that it works a bit like the stock market, that BTC would be similar to gold for some investors, etc.
You have to take into account the level of familiarity that people have with the technology in order to explain it in a way that they understand, I think that's perhaps the most important thing
It's different having to explain how it works to an IT person than to someone who doesn't use computers or smartphones
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