John Winchester created a journal in which he placed all of his most important information that he learned during his career as a hunter. In "Pilot", he left it for his sons Sam and Dean to find and to guide them. The Winchesters consult the journal frequently for guidance with matters they are unfamiliar with.
Along with the laptop that Sam owned, the journal was his and Dean's most valuable asset in finding and killing supernatural entities. The journal was John's "single, most valuable possession". The journal is believed to be extensive and is also believed to hold all of the information needed to defeat Azazel whom he had spent his entire hunting career looking for.
Sam and Dean eventually learn that the physical journal itself is actually one ordered by Henry Winchester before he disappeared for his own use. Apparently despite hating the man, for "running out on him," John still kept it and used it for himself when he became a hunter.
The journal falls into Mary Winchester's hands upon her resurrection, ten years after Dean inherited it.
- Season One
- Season Two
- Season Three
- Season Four
- Season Five
- Season Six
- Season Seven
- Season Eight
- Season Nine
- Season Twelve
- It should be noted that in the published version John states it was given to him by another hunter who told him to write everything down. However, in the show it was originally meant for his father, and John inherited it when Henry disappeared.
- In the animated series, the journal came from John's friend Fletcher.
Alex Irvine, in association with Harper-Collins Books, wrote and published the official Supernatural - John Winchester's Journal, also available in E-book format. However it only loosely follows canon.