Docker is a container management software for Linux. Each container is functionally similar to an OpenVZ VPS, allowing isolation of applications on a server. This isolation enables different versions of the same software or conflicting applications to run on the same server. For example, MySQL 5.7, MySQL 5.6, and MariaDB 10.1 can run simultaneously in three separate Docker containers on one server. However, Docker surpasses OpenVZ in its more flexible Linux kernel version requirements. OpenVZ kernels remain stuck at 2.6.32 (stable) and 3.10 (development), while Docker runs on any Linux kernel above 3.10. My server currently uses Linux kernel 4.9 (for BBR support), which clearly cannot run OpenVZ but works perfectly with Docker....