The Word of God, there being several of them, was written and depicted by Metatron, a angel who ciphered it while God was forming creation.
It is breakable, however the designated prophet to reading it, can re-connect it, if it were to break.
Background
Documentation
It was written while God was in the process of creating life. It was eventually placed in the Earth's core, "the Vault of the Earth".
Sometime in 2012, Dick, a Leviathan, the leader, through grok and heavy excavation, pries it from its safe.
The Girl With The Dungeons and Dragons Tattoo
Top Leviathan, Dick Roman, sent another Leviathan to retrieve it at a airport, but Sam intercepted it. They don't know what it is or does.
Reading Is Fundamental
Having it, Dean breaks the shell that contains the script, which causes loud supernatural simultaneous lighting. They bring it with them, and Kevin, a boy reluctantly turned into a prophet, runs away with it, but Sam gets it back.