When something is working, it seems to make sense to you. For example, we all know that a car burns gas, and uses the energy to run a motor that turns the wheels to make it go. Gas--> motor--> wheels--> Go! It seems simple. The same is true of an operating system. You turn it on, it boots up, some text goes across the screen, then the windows pop up and you're ready to go. Boot--> text--> windows--> Go! Its easy, until something breaks. You never really understand how complicated something is until it breaks.