In Quantum Chromodynamics, the strong coupling constant αs runs with energy scale Q according to the one-loop beta function: αs(Q) = αs(μ)/(1 + b₀·αs(μ)·ln(Q/μ)), where b₀ = (11Nc−2Nf)/(2π). For Nc=3 colors and Nf<17 flavors, b₀>0, so αs decreases at high Q (asymptotic freedom) and grows at low Q toward confinement. The QCD scale ΛQCD ≈ 200 MeV marks where the coupling becomes non-perturbative.