To a techie:  Bitcoin is Money Over Internet Protocol

To an economist:  Bitcoin is irreversible, ultrasecure, mathematical cowry shells

To an entrepreneur:  Bitcoin is digital money Lego--you can use it to build anything

To grandma:  Bitcoin is money that you can send like email

To a merchant:  Bitcoin is no service fees, no specialised hardware, and no chargebacks

To a first generation immigrant:  Bitcoin is 90% off Western Union fees for everyone

To Joe Everyman:  Bitcoin is a 5% discount on online shopping

To your great-grandchild:  Dollar bills were how people paid for things before we had Bitcoin