A giant star was a type of star. They usually generated less heat than smaller stars, and the outer atmosphere was explorable using a well-shielded scout vessel. Giant stars typically occurred when the hydrogen fuel of the star had been consumed, causing the star to expand, possibly consuming inner planets in a star system. Systems with giant stars were capable of supporting terrestrial planets. Red giants were the most common form of giant star.
As the star aged, it would vary in size and brightness. As it continued to burn, it would produce heavier elements until it exhausted it fuel. At that point, it would collapse into a white dwarf or neutron star. The outer layers had a chance of creating a supernova. On rare occasions, the giant star's core could become a black dwarf.