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. By the time that Mary is trapped in an alternate reality, the Winchesters own it once more.
- Season 1
- Season 2
- Season 3
- Season 4
- Season 5
- Season 6
- Season 7
- Season 8
- Season 9
- Season 12
- Season 13
- 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.
- John pinned his Marine service medals on the inside cover.
- Following Dean using the journal to find out about Abaddon's protégé in season 9's First Born, the journal did not appear again until it was given to Mary Winchester in season 12's Mamma Mia. However, it was still not used for a case from First Born until season 13's The Rising Son when Sam found information on a Hell Gate Asmodeus was trying to open and later information on the Princes of Hell.
- Prior to season 10, the journal was used at least once a season to help on a case. There ended up being a gap of three whole seasons when the journal was not used to help on cases though it did make cameos in one of those seasons. In the other two, it did not appear at all.
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.