It's a collection of tubes.
"Series of tubes" actually
Although going by what turns up on the Internet, I'm more inclined to believe the Big-truck analogy instead.
My own personal pet-peeve is when people fail to capitalise the "I" in Internet. When you're refering to the Internet, then you capitalise it, which is pretty much every occurence in the newspapers and the like, despite that they continue to use the lesser 'i'.