Gamma-ray Bursts (GRB) are very short-lived but very intense bursts of gamma-ray radiation. If we take a look at the electromagnetic spectrum we can see that GRBs are even higher in energy than X-rays, making the events which create them in such high quantities and at such a short timescale extremely high-energy events.
Stars are formed in clouds of gas and dust, known as nebulae. Nuclear reactions at the centre (or core) of stars provides enough energy to make them shine brightly for many years. The exact lifetime of a star depends very much on its size. Very large, massive stars burn their fuel much faster than smaller stars and may only last a few hundred thousand years.