Originally Posted by
NewbieRunner
Think of
Schengen as the "united states of Europe". You go through passport control when you first enter the area but once inside there's no further passport control. Note that the UK and Ireland are not in Schengen.
Not the best comparison since the US doesn't really allow international transfers without going through passport control as Schengen does. So think of it as a more convenient version of the "United States of Europe" :P