Some truly motivated authors start with a blank journal then go all scrapbook queen on it. From 'zine clippings to fabric swatches, there is no detail uncatalogued. Hell, they even paste calendars, perfume samples, and recipes in there.
Opting for all the conveniences of tech, there are those who have turned Pintrest into their series bible. The uber visual site lends itself to using reference images to map their worlds and peeps, plus it allows the author(s) to share it with their fans.
Then there are those supremely analytical authors who create Access Databases with tables and queries (the other kind of query). The series as a constantly growing beast has every bit of minutiae recorded, tagged, and logged. Book, chapter, page number and paragraph.
Me? I'm a mid-effort sort of tracker. Since I outline my books, everything I need is in that primordial Word doc. One doc per book. Easy copy and paste from one book's outline to the next. Additions added as bullet points under the headings and sub-headings. Score one for Team Plotter.
Here's an example from my Spring 2016 release NIVURN:
Challenges of Environment:
£ Challenges: Terrain = The ground is frozen solid, permafrost. It is all ice and snow on the surface.
o Burrowing down to the magma layer is highly risky and hazardous. The permafrost is stable but unyielding cold. Below that is silt, shifting and unstable. The ground caves in with any type of digging.
o There are short willow trees and plants that grow horizontally in the thin “melt sheet.” These feed the herbavores.
o The coast of Nivurn is littered with thermokarsts – marshy islands amid the thawing permafrost caused by the tides of the Pogichan Sea. At high tide, the buildings are on silts and seem to be house-ships on the sea.
£ Challenges: Food = Vadrigyn eats rocks. In a frozen tundra, there simply aren’t any. She’ll have to harvest/steal them from others. It makes her highly predatory.
£ Challenges: Weather = She’s a fire-child; she doesn’t do cold and wet. It’s actually detrimental to her body. The longer she stays in Nivurn, the weaker she becomes.
£ Challenges: Shelter: Tents (migrant) or igloos/ice villages (stationary).