Stars are the main population of galaxies. The star is red-hot balls, like the Sun. However, the world of these celestial bodies is unusually diverse. There are stars, giants and supergiants. For example, the diameter of the star alpha in the constellation of Hercules 200 thousand times greater than the diameter of the Sun. The light of this star goes the distance to Land over 1200 years (and the speed of light is 300 thousand kilometers per second). If you could fly on the plane of the equator giant, then it would require 80 thousand years.
There are also star-dwarfs, which are much inferior in size to the Sun and even the Earth. The substance of such stars is notable for its unusual density. Thus, one liter of the substance of the "white dwarf" Kuiper weighs about 36 thousand tons. Match made from such substances would weigh about 6 tons.
A greater density of neutron stars have. The average density of matter reaching 100 million tons per one cubic centimeter. Such stars are composed mainly of nuclear particles - neutrons and essentially represent a huge atomic nucleus.
Stars differ in surface temperatures from a few thousand to tens of thousands of degrees. Stars red are considered "cold". Their temperature is only about 3-4 thousand degrees. The Sun was high, with yellow-green color, the surface temperature reaches 6 thousand degrees. White and blue stars are the hottest, their temperature exceeds 10-12 thousand degrees.
Many stars have similar hot satellites. In the Universe there are double, triple and more complex stellar system. These star families have with each other the forces of mutual attraction and revolve about their common center of mass.
The stars in the Galaxy are moving at a very complex trajectories. With great speed (about 250 kilometers per second) rushes in world space and the Solar system. She makes a complete revolution around the galactic centre for 180 million years.