Aspects of Higgs physics and physics beyond the Standard Model at LHC and $e^{+}e^{-}$ linear colliders

Recent developments in prospects of searching for Higgs particles and testing their properties at the LHC and at TeV e+e- linear colliders are summarized. The discovery limits of supersymmetric particles at the LHC are presented and the accuracy is explored with which the fundamental SUSY parameters in the context of supergravity models can be determined at high-luminosity linear colliders. Finally, new discovery limits for gauge bosons in left-right symmetric models at the LHC are presented.