Operating-system level virtualization on FreeBSD
Operating-system level virtualization is available in a few different ways on FreeBSD.
chroot
FreeBSD provides support for chroot via chroot(8). This utililty changes the root directory of the current process, such as a terminal, and all child processes created within it.
Jails
Jails have been a feature of since FreeBSD 4.X. Its a far more comprehensive solution compared to chroot. Whereas chroot only deals with the file system aspect of the operating system, jails are similar to running a sandboxed FreeBSD system, with its own processes, files, users and is nearly indistinguishable from the real OS.
Application Containers
Docker and Jetpack application containers which have been ported and specifically tailored to FreeBSD.
Jetpack is an application container based on Jails, but follows the App Container Specification which is similar to Docker's way of using Dockerfiles.