Maybe it's because of the importance this collection of characters, events, and timelines has that I compare it to a book that so many people give a central role in their lives, or maybe it's just because I heard it referred to this way once and that is what stuck in my mind for all of time, but for whatever reason, I think and call my notes my author's bible.
I mostly use Scrivener for my word processor when I'm working on one of my novels, so I put my author's bible down in the "index" section, but when I am using a "normal" word processor like Word I put all of that information at the bottom of the document so that it is only a glance away.
When I'm writing on paper (which is where I do my rough drafts... a luddite quirk of mine) I have scraps of papers and comments everywhere, scraps that will later become a more permanent part of my bible. Names, ages, connections between people, times when big events happen...everything I need to know before introducing something new.
My author's bible keeps my stories from having too many inconsistencies.
If you have ever read a book where the character's hair changes length (or--horrors!--color), his smile goes from crooked to straight and perfect, or her background information changes (I see this too often, even by traditionally published authors who theoretically have professional editors checking for these inconsistencies) it can really throw you off.
And unlike movies, we don't have people hanging around checking to make sure all of the details match up (and if you've ever watched the Lord of the Rings movies and seen Legolas's eyes changing color from scene to scene, you'll know that those people on set don't catch everything either). Which is where the author's bible comes in.
I keep track of all of my characters, their background info, relationships with the people around them and people that have influenced them in the past, and dates of important life events. I keep track of places, where they are, when they come into play, what happened there. I keep a timeline (and this is the most edited part of my bible because I add even seemingly minor events onto my timeline) and I check again and again to make sure that my details are correct.
An example of something that exists in the bible for my novel The Talented:
Adrienne's pendant necklace--a gift from her dad when he consigned her to the army, used to be her mother's, she wears it on a leather cord around her neck, the pendant has a stylized knot shape and is usually tucked under her clothes. She fidgets with the cord when she's nervous.
From this short note I know everything that I need to know about the necklace--where she got it, whose it was, what it looks like, and what she does with it.
Looking at this I know she wears the pendant on a leather cord--so I'll never have her rubbing her fingers over the chain. I know that she hides the pendant under her clothes, so no one will comment on it unless she--for some reason--doesn't have it tucked in (which would probably be an important detail). And I know that she fidgets with it, which A. means that she has a nervous habit and B. suggests that it is important to her.
Of course, looking at this I, as the author, know other things about it. She was 4 when her dad conscripted her to the army, and it was soon after her mother's death. She's a private person who would never want to be seen as sentimental or girly, which would explain the leather cord and why she hides the pendant. And she thinks of her mother more than she would ever admit, which would be why she is drawn to the necklace when she is uncomfortable as well as another reason why she keeps it hidden.
And I could write all of this in, but I don't need to. The original entry has all of the salient details--all of the things that I might accidentally get wrong. I might say that she has it on a chain, not a cord. I might say that her mother gave it to her before she died, rather than her father as a sort of sorry-I'm-giving-you-away present. I might have it hanging in front of her shirt and have someone comment on it without it being a big deal.
And for the most part, these would be small things (especially the last), but too many small things can lead to a big problem.
Everyone struggles with mechanics, plot holes, and inconsistencies. To me, the author's bible is one way to eliminate (or at least reduce) the latter.
So, what do you do to keep track of all of these things, and how detailed is your bible? I'd love to hear.