Xen is an open-source virtualization product. VMware is based on an academic project developed at Stanford, while Xen is based on an academic research project developed by a professor at Cambridge University in Great Britain. Rather than creating a proprietary product like VMware, the developers decided that Xen would be an open-source virtualization product. The goal was to place a commercial company behind Xen to provide the ability to deliver to market, to provide support, and so on. Therefore, a company called XenSource was founded, funded, and located in Cambridge, UK. Ultimately, that company moved to Palo Alto, CA, to act as the commercial sponsor to shepherd Xen and help it become accepted within the technology industry. XenSource was subsequently purchased by Citrix.