Credo is the token you earn when someone you don’t know sends you an unsolicited email. You can use the Credo you earn to send your own emails to people you don’t know, trade it for other currencies, or hold onto it as its power increases.
The main goal of Callisto is to research and develop a reference implementation of a self-sustaining, self-governed, self-funded blockchain ecosystem and development environment. Callisto aims to establish a secure and contribution-friendly environment for further protocol development and improvements. It will rely on a built-in system of smart-contracts to achieve this goal.