openSUSE Tumbleweed

Tumbleweed is the rolling-release variant of openSUSE: instead of versions it delivers a constant stream of updates, so the system never grows "old" and never needs a big upgrade. The idea was launched in 2010 by kernel developer Greg Kroah-Hartman and in 2014 became openSUSE's main rolling edition.

What makes Tumbleweed unusually reliable for a rolling distribution is openQA, an automated test system that trial-runs every candidate snapshot before it reaches users. Btrfs snapshots also make it easy to roll back an update that misbehaves anyway. The stable, versioned counterpart is openSUSE Leap, and the paid server cousin is SLES.