# Values and types

What kinds of value a Jadpo program works with, how you give a value a
meaning in your business, and when one type can stand in for another.

The idea behind all of it: **how a value is stored is not what it means**. An
email address and a username are both text underneath, and an order ID and a
customer ID are both UUIDs, but Jadpo treats them as different types. A value
becomes a type only by being checked against that type's rules, and the
compiler never converts between types without being asked.