Executive Summary : | The Large Hadron Collider (LHC) has discovered the Higgs boson, which will play a crucial role in analyzing and detecting deviations from the standard model (SM). There are several profound questions associated with the Higgs sector of the SM, such as the origin of electroweak symmetry breaking, whether Higgs is a composite object of strong dynamics, if there is $CP$ violation, the hierarchy problem caused by fine-tuned cancellations of large quantum corrections to the Higgs mass, the flavour problem of the SM, the Electroweak Phase Transition, and one prime candidate for Dark matter, the scalar dark matter. To address these questions, it is essential to obtain more precise measurements of the properties of the discovered Higgs, such as couplings, decay width, and mass, to determine if the Higgs behaves like the SM Higgs boson or deviates from standard behavior. The LHC will continue to run at peak energy for the next two decades, providing approximately 3$ab^{-1}$, which is 20 times more data than the current dataset. Any deviation from the SM predictions in these measurements can signal physics beyond the SM. The High-Luminosity LHC is expected to achieve precision of many couplings of the Higgs boson at a few percent level, constraining a wide range of new physics models and providing indirect signatures of beyond the SM (BSM) physics. The self-interactions of the Higgs boson are crucial to shape the profile of the Higgs potential and its consistency with the SM. |