Short answers, pulled from the story.
The rings of Neptune were first detected as arcs during simultaneous stellar occultation observations on the 22nd of July 1984 by teams at La Silla Observatory and Cerro Tololo Interamerican Observatory in Chile. The full ring system was imaged in 1989 by the Voyager 2 spacecraft during its flyby of Neptune.
Neptune has five principal named rings: Galle, Le Verrier, Lassell, Arago, and Adams, listed in order of increasing distance from the planet. There is also a faint unnamed ring coincident with the orbit of the moon Galatea.
The Adams ring contains five distinct arcs named Fraternite, Egalite 1, Egalite 2, Liberte, and Courage, after the ideals of the French Revolution. These arcs are clusters of ring particles occupying a narrow range of orbital longitudes from 247 to 294 degrees, and their continued existence puzzles scientists because basic orbital dynamics predict they should spread into a uniform ring within years.
The arcs are unusual because orbital mechanics predicts they should disperse into a continuous ring over a short timescale, yet they have remained roughly stable since their first detection in 1980. The most likely explanation involves a gravitational resonance with Neptune's moon Galatea, but measurements from the Hubble Space Telescope and Keck telescope in 1998 showed the rings are not in the predicted co-rotational inclination resonance with Galatea.
Neptune's rings are composed of extremely dark material, likely a mixture of ice and radiation-processed organic compounds similar to those found in the rings of Uranus. Their geometrical albedo is about 0.05, and their dust fraction by cross-section area ranges between 20% and 70% depending on the ring. Infrared observations from the James Webb Space Telescope detected a weak absorption band at 3 micrometers in the ring material.
Voyager 2 passed within 4,950 kilometers of Neptune's atmosphere on the 25th of August 1989 and provided the first definitive images of the ring system. The flyby confirmed that the partial occultation signals observed from Earth during the 1980s were caused by the arcs in the Adams ring, and it led to the discovery of six inner moons of Neptune including Galatea, which plays a key role in the arcs' stability.