There are a wide variety of Linux VPS solutions available in today's marketplace. Currently, the most popular variants include Xen and Virtuozzo/OpenVZ. Older systems such as UML (User-Mode Linux) were once popular, but are no longer as widely used. When considering the operating system of a VPS, one must look at it from two points of view: that of the host, offering VPSes on his/her dedicated server, and that of the users, making use of the VPS. Linux has been and continues to be the most popular VPS hosting platform, and many Linux distributions now include a stock installation which will allow a user to host a number of VPSes on their hardware. Depending on the VPS platform, the user OSes available are usually variants of Linux, although some vendors use platforms which will allow them to sell Solaris, FreeBSD and other non-Linux VPSes.