The float value
Every skin has a hidden float between 0 and 1. Lower = cleaner. It maps to five exteriors: Factory New (0–0.07), Minimal Wear (0.07–0.15), Field-Tested (0.15–0.38), Well-Worn (0.38–0.45), Battle-Scarred (0.45–1).
Why it matters for price
A Factory New copy of the same skin can cost several times a Battle-Scarred one. Collectors chase extreme floats (0.00x or max) which carry big premiums.
On skin1
Every listing shows its exact float and a colored wear bar so you know precisely what you're buying before you pay.