A Main Sequence Star is a type of star that is in the stable phase of its life cycle, where it fuses hydrogen into helium in its core. This process generates energy, allowing the star to shine brightly for billions of years. Our Sun is a prime example of a main sequence star, classified as a G-type star. Main sequence stars vary in size, temperature, and brightness, ranging from small red dwarfs to massive blue giants. They are crucial for understanding the evolution of galaxies and the formation of planetary systems, as they provide the necessary conditions for life as we know it.