Alpha_s: from DIS to LEP

The strong coupling alpha_s is a fundamental parameter of the Standard Model. In comparison to parameters like alpha_em and M_Z it is relatively poorly known. However the precision of alpha_s measurements has improved dramatically in recent years. More than twenty different types of process, from lattice QCD studies to the highest energy colliders, can be used to measure alpha_s accurately. The most precise determinations now quote uncertainties in alpha_s(M_Z) of less than 5%. There is also a remarkable consistency between the various measurements. The present review provides an update on alpha_s measurements from the past year.