DragonFly belongs to the same class of operating systems as other BSD-derived systems and Linux. It is based on the same Unix ideals and APIs and shares ancestor code with other BSD operating systems. DragonFly is differentiated from other operating systems in its class by, among others, the HAMMER file system, Virtual Kernels, swapcache, and the pervasive use of soft token locks. DragonFly provides an opportunity for the BSD base to grow in an entirely different direction from the ones taken in the FreeBSD, NetBSD, and OpenBSD series.