y is by default interpreted as VerticalBar[x,y]. Used in mathematics to indicate that x divides y. Also sometimes called Sheffer stroke, and used to indicate logical NAND. Not the same as \[VerticalSeparator], which is drawn longer. Not the same as \[LeftBracketingBar] and \[RightBracketingBar], which are drawn with a small tee to indicate their direction. | is the alias for \[VerticalSeparator]. The alias for \[VerticalBar] has a space at the beginning. See The Mathematica Book: Section 1.10.8, Section 3.10.4. See also: \[RawVerticalBar], \[NotVerticalBar], \[DoubleVerticalBar], \[Backslash], \[HorizontalLine].