Polaris
Polaris, Alpha Ursae Minoris, is the bright star closest to the north celestial pole. It is also known as the North Star, the Lode Star, or the Pole star.
Because it lies nearly in a direct line with the axis of the Earth's rotation "above" the North Pole -- the north celestial pole -- Polaris is apparently motionless from the Earth, and all the stars of the Northern sky appear to rotate around it. Therefore, it makes an excellent fixed point from which to draw measurements for celestial navigation.
Due to precession of the equinox, other stars in the Northern hemisphere have been and will likely again become the North star over thousands of years; Thuban was pole star in the past, and Vega will be in future. The star, visible to the naked eye, that is closest to the south celestial pole is Sigma Octantis.
Polaris is 431 light years (132 parsecs) from Earth, according to measurements made by the Hipparcos satellite. It is an F7 supergiant (Ib) or bright giant (II), with two smaller companions: an F3 V main sequence star about 2000 AU away and a close companion in an orbit with a 5 AU semi-major axis. The main star is a Population II cepheid variable, the pulsations of which cause it steadily cycle between 8% brighter than its average luminosity and 8% dimmer (0.15 magnitudes in total) with a 3.97 day period.