Have a look at this article: http://en.wikipedia.org/wiki/Serial_comma
Student or Learner
We know that one use of comma is to list things.
I have a pencil, an eraser and a ball pen.
But I don't understand why, in some books we see a comma before 'and'?
It is orange, black, and white.
It's optional. I generally use it, but it's fine without. I do agree with MikeNewYork that it can make things clearer sometimes, but many who don't normally use it would use it in such sentences.
It's called a "ballpoint pen" in my experience.
You can use both in BrE.