A galaxy is a huge group of stars, dust, gas, and other celestial bodies bound together by gravitational forces. There are spiral, elliptical, and irregularly shaped galaxies. Galaxies contain anywhere from 100,000 to 3,000,000,000,000 stars.
There are three major types of galaxies: spiral (with arms), elliptical (no arm), and irregular (without rotational symmetry). Galaxies radiate a continuous spectrum of energy. Some radiate radio waves, X rays, and infrared, and ultraviolet (UV) radiation.
The galaxy that is nearest to our galaxy is the Sagittarius Dwarf galaxy, which is about 24 kiloparsecs or 80,000 light years from us. The Large Magellanic Cloud is another close galaxy; it is about 50 kiloparsecs from us.