Structural and dynamical properties of NGC 188. Left: surface density profile derived from the GAIA DR3 membership catalog. The solid line represents the best-fit King model, yielding a core radius, R_c = 2.00 ± 0.15 pc, and a tidal radius, R_t = 51.2 ± 4.3 pc. The background density level, ρ_bg, is subtracted to highlight the cluster’s extent into the halo. Right: mass segregation ratio, Λ_MSR, as a function of the number of the most massive stars, N_MST. The significant deviation from unity (Λ_MSR > 1.2 for the top 50 massive stars) confirms a strong mass segregation effect, indicating that the cluster is dynamically well relaxed because of its 7 Gyr age.