M5 is, under extremely good conditions, just visible to the naked eye as a faint "star" near the star 5 Serpentis. Binoculars or small telescopes will identify this cluster as non-stellar while larger telescopes will start to show individual stars, of which the brightest are of apparent magnitude 12.2.
M5 was discovered by the German astronomer Gottfried Kirch in 1702 when he was observing a comet. Charles Messier found it in 1764 and thought it a nebula without any stars associated with it. William Herschel resolved individual stars in the cluster in 1791, counting roughly 200 of them.
M5 is not to be confused with the much fainter and more distant globular Palomar 5 which is situated nearby in the sky.