3. Campfire Farms (They earn you hearts and XP)
Campfire Farms are important in Horizon Zero Dawn as they are a great source to earn some Hearts and XP (Experience Points). If you are in search of some rare machine hearts look for the Campfires near the enemies. Once you are able to defeat the enemies near the Campfire, you can collect hearts and XP will automatically be added. So Campfires are the easiest way to get both of these important things.
Fire is an another important thing in Horizon Zero Dawn. It holds a great elemental power and it helps you find ways in the darkness and lets you scare away a lot of enemies as well. so at some points, you can use it as a weapon too. It can do a heavy irreversible damage to the damaged dinosaurs such as Glinthawks and Ravages as well.