Why is white box testing sometimes called glass box testing?

Question

In some references, I have found that white box testing is sometimes called glass box testing. I would like to know what are the reasons behind that.

Answer 1

Black Box Testing: You can not peek inside the box (i.e. the code), all you know is the interface/API of the system under test

White Box Testing: You can peek inside the box. White, because it is the "oposite" of black. I have not heard of Glass Box Testing before, but it actually makes sense, because it emphasizes the "you can peek inside" notion.