QCD and new strong dynamics at LHC

Quantum chromodynamics (QCD) is a successfully-tested theory of strong interactions. It describes extremely well the strong interaction of hadrons from low energy to the highest energy available at colliders. In this colloquium I will describe the making of QCD and its success and also recent study of QCD from string theory. With understanding QCD I will then attempt to describe the strong-dynamics models of electroweak symmetry breaking and their signatures at LHC.