All stars produce light (and other kinds of energy) through nuclear reactions, using the energy stored in the tiny nucleus at the center of atoms. These reactions make the star so hot that it glows—it's like an enormous ball of fire, giving out light and heat.
We can say that the stars emit light on their own because of "burning" but this burning is not like the usual burning of a paper. A star is a huge ball of gas called hydrogen. When two hydrogen nuclei fuse togetehr to form a helium nucleus some energy is released. This process is called nuclear fusion. The energy released in a fusion reaction heats up the other materials (other hydrogen and helium atoms ) nearby. This heating eventually grows out from the core to the outside. The radiation coming out of the star's surface is in the form of heat and light. Note that the hydrogen nuclei do not really burn: they only fuse to form helium and the energy released in the process is in the form of heat and light.
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