The paper discusses theoretical and phenomenological aspects of two-Higgs-doublet models (2HDMs), focusing on their scalar sector, flavor conservation, and CP violation. It reviews various 2HDM scenarios, including type I, II, lepton-specific, and type III models, which differ in their symmetry structures and flavor violation properties. The scalar potential of the 2HDM is analyzed, with emphasis on vacuum stability, symmetry constraints, and the role of CP violation. The paper also explores the phenomenology of charged Higgs bosons and their decay modes, as well as the implications of different symmetry assumptions on the model's predictions. It discusses the role of discrete symmetries in suppressing flavor-changing neutral currents (FCNCs) and the importance of the parameter tanβ in determining the interactions of Higgs bosons with fermions and gauge bosons. The paper also addresses the experimental challenges of distinguishing between different 2HDMs at the LHC, including the branching ratios of Higgs decays and the constraints from collider experiments. The review concludes with a discussion of the implications of CP violation in 2HDMs and the potential for these models to explain phenomena such as baryogenesis and the observed muon g-2 anomaly. The paper highlights the importance of understanding the scalar sector of the 2HDM in the context of the Standard Model and its extensions, and emphasizes the need for further experimental and theoretical studies to probe the parameter space of these models.The paper discusses theoretical and phenomenological aspects of two-Higgs-doublet models (2HDMs), focusing on their scalar sector, flavor conservation, and CP violation. It reviews various 2HDM scenarios, including type I, II, lepton-specific, and type III models, which differ in their symmetry structures and flavor violation properties. The scalar potential of the 2HDM is analyzed, with emphasis on vacuum stability, symmetry constraints, and the role of CP violation. The paper also explores the phenomenology of charged Higgs bosons and their decay modes, as well as the implications of different symmetry assumptions on the model's predictions. It discusses the role of discrete symmetries in suppressing flavor-changing neutral currents (FCNCs) and the importance of the parameter tanβ in determining the interactions of Higgs bosons with fermions and gauge bosons. The paper also addresses the experimental challenges of distinguishing between different 2HDMs at the LHC, including the branching ratios of Higgs decays and the constraints from collider experiments. The review concludes with a discussion of the implications of CP violation in 2HDMs and the potential for these models to explain phenomena such as baryogenesis and the observed muon g-2 anomaly. The paper highlights the importance of understanding the scalar sector of the 2HDM in the context of the Standard Model and its extensions, and emphasizes the need for further experimental and theoretical studies to probe the parameter space of these models.