Scientists believe that nearly 15 billion (15 x 109) years ago the universe originated in a huge explosion, called the ‘Big Bang’. At the time of big bang, the size of the universe was just like a point and all matter, energy, forces were condensed into this point of zero volume and infinite density. Thus the big bang is the creation of everything - all space, energy, force, radiation and even time. The concept of time has no meaning before big bang. In this article, we shall try to explain how a star is born from the giant molecular clouds of hydrogen and helium. Then how a star is evolved and what is the ultimate fate of it. The end products of a star may be a white dwarf or a neutron star. But for a massive star, ultimately it may end up to a black hole by ongoing gravitational collapse.