A container, however, is based on a shared operating-system kernel. This, as James Bottomley, Parallels‘ CTO of server virtualization and a leading Linux kernel developer, explained at the Linux Collaboration Summit in March 2014, containers are much lighter and more efficient than hypervisors. Instead of virtualizing hardware, containers rest on top of a single Linux instance. This means you can “leave behind the useless 99.9 percent VM junk, leaving you with a small, neat capsule containing your application.”