Recent results on tests of QCD from a variety of experiments at HERA, TevaTron and LHC are reviewed. Measurements of jet, $W$ and $Z$ boson, photon and heavy-flavour production are presented. Besides their intrinsic interest, these measurements provide experimental constraints on Standard Model processes that constitute background to new physics and are used to extract values of the coupling of the strong interaction and to constrain the proton parton distribution functions. New developments in theoretical calculations relevant for the comparison to the measurements are also discussed.