Sunspot

Regions on the Sun’s surface that appear dark because they are cooler than the surrounding photosphere, typically by ~1500-1800 K. Sunspots develop and persist for periods ranging from hours to months, and are carried around the surface of the Sun by its rotation.
Sunspots travel in pairs (north and south magnetic poles). The pairs are due to magnetic flux tubes on the surface of the Sun that carry energy away causing the surface to be cooler than the surrounding material.


Image source: http://media.skyandtelescope.com/images/Sunspot-group_l.jpg.