Durability is the health of an item.
The base durability is determined by the Quality of the item and how many times it has been repaired.
Once an item reaches low durability it will get a Red outline indicating they will soon break if not repaired.
Once an item reaches 0 Durability it will be destroyed and removed from your inventory.
The base durability of an item can be increased by reinforcing it with glue.
Note: Repairing an Item will reduce the base durability of an item.