Whenever your Linux system boots up, certain daemons(equivalent of windows services) are loaded into the memory in background. These daemons provide certain functionalities & launch certain applications in some events. Daemons run in background all the time from bootup & get into action when a particular event happens on a system.
For E.g. You plug a pendrive in your computer & after a few seconds you see a nautilus window with the pendrive contents. This is due to the “HAL Daemon” which monitors the hardware & once it detects the new hardware i.e. pendrive in our case it reports to the GNOME about it & simultaneously mounts it & launches Nautilus. HAL is a critical daemon in a Linux system but not all others are & so we must disable them. Disabling unwanted daemons helps in freeding up valuable memory resources & also helps in making the boot faster. Some daemons when kept running also open up potential loopholes for hackers to exploit.
