systemd is a system and service manager for Linux. It provides aggressive
 parallelization capabilities, uses socket and D-Bus activation for starting
 services, offers on-demand starting of daemons, keeps track of processes using
 Linux control groups, maintains mount and automount points and implements an
 elaborate transactional dependency-based service control logic.
 .
 systemd is compatible with SysV and LSB init scripts and can work as a
 drop-in replacement for sysvinit.
 .
 Installing the systemd package will not switch your init system unless you
 boot with init=/lib/systemd/systemd or install systemd-sysv in addition.