A supernova is a star that ends its existence by exploding and leaving behind a neutron star or a black hole. All of the heavy matter and large amounts of many elements in the universe were produced by supernovas. All human bodies contain some of these elements.
Stars that end as supernovas are usually much larger than the Earth's sun. Smaller stars, yellow dwarfs like the sun, first expand to become red giants and then condense to become cooler white dwarfs and eventually black dwarfs. A white dwarf in a binary system can also magnetically pull mass from a nearby star in the same system until the pressure in its core increases to the point of explosion.