An outflow of hot gas, analogous to the solar wind, from a galaxy that has recently undergone a high burst of star formation or has an active galactic nucleus. Galaxy winds are streams of high speed charged particles blowing out of galaxies with speeds of 300 to 3,000 km s^-1. In the case of starbursts, galactic winds are powered by stellar winds driven by massive stars and supernova explosions. Galaxy winds contain a mixture of extremely hot metal-enriched supernova ejecta and cooler entrained gas and dust. Outflowing material has been observed at great distances from galaxies (10 to 100 kpc). In some cases they escape the galaxy potential well and pollute the intergalactic medium with heavy elements. A prominent example is the superwind of the starburst galaxy M82.