Design systems
Design systems are the single source of truth for both the design and implementation of a digital product which includes working code, design tools and resources, and human interface guidelines.
Examples
Material Design System - Google
Workday Canvas - Design system of Workday
Carbon Design System from IBM
https://adele.uxpin.com/ - The repository of publicly available design systems and pattern libraries
http://styleguides.io/ - Collection of design systems