A design system is an all encompassing artefact that houses pattern libraries, style guides, ui kits and all documentation that would aid a team so they can create and build in unity and true collaboration.
With the term prefixed with design, many believe this artefact only speaks to designers , this is an incorrect notion, that limits a teams growth and unity. Like a vicious cycle, the design systems born from this conceit, those systems are only for designers. A design system is for an entire team, from managers to marketers, from developers to designers and all team members in between.
A design system is no a static artefact, in both literal and metaphoric sense. It should be continuously updated, with increasing velocity and motion. It should be filled with real world examples, testing scenarios and as much report of success as it would failure.
A design system may be initiated by one but it is owned by as many people as possible, with just as many buy in to it's existence.
Design systems can be slow to begin, as all large scale processes can do when they hold weight and poise.