A giant supermassive black hole is just remains of a once great star, and it collapsed into on itself, pressurizing so much gravity that it makes a hole in time and space in this universe, sucking in anything, so basically it is just a hole of gravity.
A supermassive black hole.
The middle of the milky way is a black hole and a black hole cannot be made up as matter. The middle of the milky way has no size, but the black hole sucks the light making it look big in pictures. The actual size is nothing.
A supermassive black hole.
Keeps the whole Milky Way together
No - The volume of the Milky Way galaxy is larger than the volume of its host black hole. The accumulated mass of the Milky Way galaxy is greater than the mass of its host black hole. The density of the Milky Way galaxy is much smaller than the density of its host black hole.
The milky way was formed by stars gases and dust . The milky way also started as a black hole and stars dust and gases gathered around the black hole.
It is suggested that there is a black hole in the center of not just The Milky Way, but most other galaxies.
Fortunately, no.
Black holes are common in most galaxies. It is not odd that there would be a black hole in the middle of the Milky Way.
At the centre of our Galaxy, the Milky Way
The Milky Way appears to have a huge (even for a black hole) gravitational object at the center of it, and this is supposed by a lot of scientists to be a black hole. The arms of our galaxy sweep around the center.
They don't specifically orbit the black hole. Stars orbit the Milky Way because in general, they are attracted to the other masses in the Milky Way. The supermassive black hole is only a tiny fraction of the total mass of the Milky Way. Well, you might say that they move around the black hole, but that's only because it happens to be there. Without they black hole, they would move around the center of the Milky Way anyway.