Black holes are some of the most impressive and most fascinating objects (actually not an object, they are an empty space with great mass) found in space. The gravity is so strong due to matter has been squeezed into a tiny place, i am talking about the gravity pulls so much that even light can't get out! Imagine New York city packed into a bag; That's a black hole.
A black hole can't be seen because it pulls all the light around it as i mentioned above. However, scientists can detect black holes by observing certain behaviour of the stars around a black hole.
How Do Black Holes Form?
A typical type of black hole is produced by dying stars, with a mass greater than 18--20 times the mass of our Sun. When it burns all the hydrogen and consumes all the fuel it has, it explodes like hell, which is called supernova. After this powerful explosion, the outer parts of the star scatter into space, while the core of it collapses upon itself. If the mass of the core is great enough, this process never stops until nothing remains from the star. Then it creates a hungry hole that swallows everything.
Is Our Sun Going To Become a Black Hole?
Basic answer is no. Our sun is not big enough to cause a supernova, and does not have a great mass enough to create a black hole. After our sun burn off all of it's hydrogen, it is going to become a white dwarf which is the dead core of sun-like stars, like almost all the stars we see on the sky at night.
What's Inside a Black Hole?
The inner region of a black hole, where its mass lies, is known as its singularity, the single point in space-time where the mass of the black hole is concentrated. Once a particle crosses the event horizon, which is boundary around the mouth of the black hole where light loses its ability to escape, the particle can never leave. If you fell into a black hole, theory has long suggested that gravity would stretch you out like spaghetti, though your death would come before you reached singularity.