Control Groups, more commonly called cgroups, were introduced back in 2010 in Red Hat Enterprise Linux 6. Originally, they were just an add-on feature, and a user had to jump through some hoops to manually create them. Nowadays, with the advent of the systemd init system, cgroups are an integral part of the operating system, and each process runs in its own cgroup by default.
With cgroups, processes run in their own kernel space and memory space. Should the need arise, an administrator can easily configure a cgroup to limit the resources that the process can use. This is not only good for security, but also for tuning system performance.
So, what is a cgroup? Well, it's really just a collection of processes ...
