The average general-purpose Linux distribution launches all kinds of stuff at startup, including a lot of services that don’t need to be running. Bluetooth, Avahi, ModemManager, ppp-dns… What are these things, and who needs them? Systemd provides a lot of good tools for seeing what happens during your system startup, and controlling what starts at boot. In this article, I’ll show how to turn off startup cruft on Systemd distributions.

Source: Cleaning Up Your Linux Startup Process | Linux.com | The source for Linux information