Yes, hydrogen is the most abundant gas in the universe. It is estimated to make up about 75% of the elemental mass in the universe. Hydrogen is found in vast quantities in stars, including our own Sun, where it plays a crucial role in the process of nuclear fusion. In stars, hydrogen atoms combine to form helium through fusion reactions, releasing an enormous amount of energy in the process. This fusion reaction is what powers stars and allows them to emit light and heat.