The Standard Model (SM) of particle physics contains only one SU(2) doublet scalar field, whose remnant after spontaneous symmetry breaking, i.e., the Higgs boson, was discovered more than 10 years ago. However, there are more than enough reasons to believe that the SM is only an effective theory valid up to a certain scale, and there should be new laws of physics beyond that scale, which necessitates an extension of the SM. In this project, we will explore extensions of the scalar sector. There will be model-dependent studies, as well as model-independent ones, based on the effective theory framework. Scalar type WIMP dark matter models will be studied too. There have been some indications at the LHC for new scalar resonances, consequences of which will be explored in great detail. Indirect effects of such scalar extensions, as may be manifest in flavour physics, will be another important focus.