Every CS2 skin is generated with a float between 0 and 1. If that number lands in 0.15–0.38, Steam labels it Field-Tested. The label is what most marketplaces sort by; the exact print still matters on knives, gloves and rare patterns.
Compare wears on any skin page — Dust2pedia stores separate list prices for Factory New, Minimal Wear, Field-Tested, Well-Worn and Battle-Scarred when the catalog has them.