I don't know jack: John's revelation

I knew the relationship between John and the word in the beginning. However, it was not until today did I realize John, this one or not debatable, also had something to do with the book of Revelation?!

John is credited as the author of the Book of Revelation, relating his vision of the end of the world. http://www.stjohndivine.org/about/architecture/cathedral-symbolic 

I really don't know jack.