The paper by Gunion and Haber explores the decoupling limit of the CP-conserving two-Higgs-doublet model (2HDM), where the lightest Higgs boson's properties are nearly indistinguishable from those of the Standard Model (SM) Higgs boson. The authors define the decoupling limit mathematically and discuss the conditions under which it applies, emphasizing the importance of detecting deviations from SM Higgs couplings at future colliders. They also clarify the case where a neutral Higgs boson exhibits Standard-Model-like couplings outside the decoupling regime. The paper provides detailed expressions for the Higgs couplings to gauge bosons, fermions, and other Higgs bosons in the decoupling limit, and evaluates the first non-trivial corrections to these couplings as one moves away from the decoupling limit. The authors conclude by discussing the implications of the decoupling limit for flavor-changing neutral currents and CP-violating effects, and highlight the potential for precision measurements to distinguish between different parameter regimes.The paper by Gunion and Haber explores the decoupling limit of the CP-conserving two-Higgs-doublet model (2HDM), where the lightest Higgs boson's properties are nearly indistinguishable from those of the Standard Model (SM) Higgs boson. The authors define the decoupling limit mathematically and discuss the conditions under which it applies, emphasizing the importance of detecting deviations from SM Higgs couplings at future colliders. They also clarify the case where a neutral Higgs boson exhibits Standard-Model-like couplings outside the decoupling regime. The paper provides detailed expressions for the Higgs couplings to gauge bosons, fermions, and other Higgs bosons in the decoupling limit, and evaluates the first non-trivial corrections to these couplings as one moves away from the decoupling limit. The authors conclude by discussing the implications of the decoupling limit for flavor-changing neutral currents and CP-violating effects, and highlight the potential for precision measurements to distinguish between different parameter regimes.