Hydrogen is the most abundant element in the Universe due to its ability to fuse and create energy in stars. It is also an essential component of interstellar gas clouds and planets. When stars start to form from large clouds of gas and interstellar dust, hydrogen is the first element to condense and start to fuse. This nuclear fusion is what provides the energy to keep stars burning, and is why hydrogen is so abundant in the Universe. It was the first chemical element to form after the Big Bang.