Linux cgroups (control groups) allow limiting and accounting for resources on a system, including CPU, memory, and block I/O.
There are two completely distinct versions of cgroups. They can be referred to as "cgroup v1" and "cgroup v2." Any literature you find around on the web that doesn't specify one or the other is almost certainly about "cgroup v1."
References:
Note that this same page provides a good writeup on the issues with v1 (and rationale for v2) which may prove quite useful even for users of cgroup v1.
