Some star clusters, such as the Pleiades, have been known for some time. Others remained undiscovered until the invention of the telescope. Before that time, many of the globular clusters and smaller open clusters were visible only as fuzzy spots in the sky. Many were even mistaken for comets at one time or another. Charles Messier was one of the first astronomers to observe and catalog star clusters along with other deep sky objects. His catalog contains 51 of the brightest and largest star cluster in the night sky. Star cluster are among the easiest objects to observe in the night sky. Many open clusters, such as the Pleiades and the Hyades, are large enough to be seen with the naked eye. Binoculars will reveal a wealth of globular clusters when pointed toward the center of our galaxy near the constellation of Sagittarius. When seen through a telescope, globular clusters are arguably the most beautiful objects in the sky. Photographs do not do them justice. Atmospheric turbulence causes many of these photos to be lacking in sharpness. But when observed through a telescope from a dark location, they can take on the look of silvery glitter on black velvet. Observing star clusters can be one of the most rewarding experiences in the astronomy hobby.