Analysis of information sources in references of the Wikipedia article "OS-level virtualization" in English language version.
Jails were first introduced in FreeBSD 4.0 in 2000
treats the disk image as copy-on-write.
There are many other OS-level virtualization systems such as: Linux OpenVZ, Linux-VServer, FreeBSD Jails, AIX Workload Partitions (WPARs), HP-UX Containers (SRP), Solaris Containers, among others.
LXC now has support for user namespaces. [...] LXC is no longer running as root so even if an attacker manages to escape the container, he'd find himself having the privileges of a regular user on the host.