A G-type giant star is a type of star that has evolved from a main-sequence star, like our Sun, into a larger and cooler phase of its life cycle. These stars are characterized by their yellowish color and significant increase in size and luminosity compared to their earlier stages. They typically have surface temperatures ranging from about 4,800 to 5,800 Kelvin. G-type giants are often found in the later stages of stellar evolution, where they fuse helium in their cores. Examples of G-type giant stars include Aldebaran and Pollux. These stars play a crucial role in the chemical enrichment of the galaxy as they produce heavier elements during their lifetimes.