For the most part space seems to be empty, it however is not, it is cluttered with various types of matter, sometimes referred to as space dust. When this happens energy is released and a star is born. A star radiates great amount s of energy in the form of light, heat, x-rays, gamma rays etc. Stars, it is believed, are where more complex elements are formed.
Stars live for billions of years and go through four basic stages.
Its middle life, as our sun now is, shinning brightly and producing vast amounts of radiation. A Red Giant. And their end. At the end of a stars life it may form a planetary nebula. A red giant just keeps on expanding until all of its matter is pushed out into space.