Spectral type G refers to a classification of stars that have a surface temperature between 5,300 and 6,000 Kelvin. These stars emit a yellowish light and are characterized by their strong absorption lines of ionized calcium and hydrogen in their spectra. The most well-known example of a G-type star is our Sun, classified as G2V. G-type stars are typically medium-sized and can have masses ranging from about 0.8 to 1.2 times that of the Sun. They are often found in the main sequence phase of stellar evolution, where they spend billions of years fusing hydrogen into helium in their cores.