Abstract: After years of development, the High Intensity Gamma-ray Source (HIGS) at Duke University, the world's most powerful Compton gamma-ray source in the 1 to 100 MeV region, has recently become a dedicated light source for scientific research. Driven by kW intracavity power of a storage ring FEL, the HIGS facility produces high-intensity gamma-ray beams with a total flux of few 1E10 g/s in the few MeV to 10 MeV region. With the present configuration, the HIGS has a wide energy tuning range from 1 to 100 MeV, a high degree of polarization (nearly 100%) switchable among linear, left-, and right-circular polarizations, and a high energy-resolution with a gamma-beam energy spread as small as 0.8% (FWHM). In this talk, we will first give a review of the history and evolution of Compton light sources. We will compare different technological choices for developing Compton sources and discuss their impact on applications research.We will then focus on the HIGS facility, describing its high intensity electron beam source and its high power photon source, a storage ring based FEL.Finally, we will describe frontier research being conducted using the gamma-ray beam at the HIGS in a wide range of scientific areas from nuclear physics to astrophysics, from medicine to industry.