How credit cards changed the way we spend

[Gerald]

The clue is in the name: credit. It means belief, trust.
If you're a shopkeeper, who do you trust to repay a debt? For most of history, only someone you knew personally, which was fine since most of the people you encountered would be from the same small community.
But as cities boomed, things became more awkward.

http://www.bbc.com/news/business-41916711

I bet in the future there are only cards with all kind of stuff etc.