A G-type star is a category of stars that have a surface temperature between 5,300 and 6,000 degrees Celsius. They are characterized by their yellowish color and are part of the Hertzsprung-Russell diagram, which classifies stars based on their luminosity and temperature. The most well-known example of a G-type star is our own Sun. G-type stars typically have a lifespan of about 10 billion years and undergo nuclear fusion, converting hydrogen into helium in their cores. They are often surrounded by planetary systems, making them important for the study of exoplanets and the potential for life beyond Earth.