I give a different answer every time based on who I am talking to. Some people want a detailed explanation and others want a very simple lay-man type analogy.
BTW - I think STEEM and in particular STEEM DOLLARS is a much better gateway crypto to introduce people to. People can start using crypto here on Steemit without even realising it. Transactions super fast and fees nil with no banks involved = The penny might drop.
Really interesting point about steem as a gateway @buggedout. Because of the utility of the website, we can move from conceptual discussions to practical examples. I'll add that to my toolkit!