Using Load Order
Mods might conflict with each other by editing each others' files. So how does the game know which files to load?
Enter Load Order. loadorder.txt is a newline-separated list of mod directories to load, in order of when to load them. Mods that are loaded later can override mods that are loaded earlier.
Here is an example load order:
./mods/tombstones C:\Program Files (x86)\Steam\steamapps\workshop\content\727570\1541010614 ./mods/potatoes
The mods will always be loaded in that order. Mods that don't appear in the load order file will always be loaded first.
You'll always be able to change the mod load order from in-game, but you can also add custom entries if necessary. To do this, you'll need to figure out where the mod(s) you wish to load are located. For locally-installed mods (dragged and dropped a folder into the game's mods directory), just type ./mods/[the directory name] (for example, ./mods/potatoes). For Workshop mods, you'll have to find where the Workshop storage is. Usually this is C:\Program Files (x86)\Steam\SteamApps\workshop\727570\mod ID, but can change if you installed After the Collapse in a different Steam library folder.