  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.
