~~ Forward ~~
For many years, Debian has used the SysV init.d system to start needed daemons and set things up. But SysV can not work multi-threaded, and does not have controllable dependency resolution. Upstart was invented to address some of these shortcomings, and RedHat and Ubongo tried it, but Upstart is just not extensible enough for future needs. And so we turn to Systemd.
Systemd was developed for Linux to replace the init.d system inherited from UNIX System V and Berkeley Software Distribution (BSD) operating systems. Unlike init.d, which is scripted, Systemd is a daemon that manages other daemons, and all daemons (including systemd) are background processes. Systemd is the first daemon to start (during boot) and the last daemon to terminate (during shutdown). Systemd starts each daemon, it monitors it, and it stops it in an orderly way. And Debian will be moving to systemd when revision Jessie is released as Stable around Nov, 2014.
Why wait? Works great. Let’s learn and use it now as it’s a better paridigm, and brings Debian into the 21st century.