An Underlay package is a collection of knowledge — messages, files, and other packages — gathered into a useful collection by a curator, and updated and versioned over time. It has metadata including contact information for its curators, schemas that describe its data, and how it is maintained.
Packages are discoverable through registries, servers that host packages and provide APIs for accessing them. A default registry, Persephone, hosts a copy of every package it is told about by Underlay members.
