The optical properties of wurtzite-structured InN grown on sapphire substrates by molecular beam epitaxy have been extensively studied using optical absorption, photoluminescence (PL), and photo-modulated reflectance techniques. These studies reveal that the fundamental band gap of InN is significantly lower than the commonly accepted value of 1.9 eV, lying between 0.7 and 0.8 eV. The PL peak energy is sensitive to the free electron concentration, exhibits weak hydrostatic pressure dependence, and shows a small, anomalous blueshift with increasing temperature. The low energy gap and unusual temperature and pressure dependencies suggest that the previously reported 2 eV absorption edge may not be intrinsic to InN. The work highlights the need for further investigation into the nature of the 2 eV absorption edge and the electronic properties of InN.The optical properties of wurtzite-structured InN grown on sapphire substrates by molecular beam epitaxy have been extensively studied using optical absorption, photoluminescence (PL), and photo-modulated reflectance techniques. These studies reveal that the fundamental band gap of InN is significantly lower than the commonly accepted value of 1.9 eV, lying between 0.7 and 0.8 eV. The PL peak energy is sensitive to the free electron concentration, exhibits weak hydrostatic pressure dependence, and shows a small, anomalous blueshift with increasing temperature. The low energy gap and unusual temperature and pressure dependencies suggest that the previously reported 2 eV absorption edge may not be intrinsic to InN. The work highlights the need for further investigation into the nature of the 2 eV absorption edge and the electronic properties of InN.