aka NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster, is a globular cluster of several hundred thousand stars in the constellation of Hercules.

M13 was discovered by Edmond Halley in 1714, and cataloged by Charles Messier on June 1, 1764

About one third of the way from Vega to Arcturus, four bright stars in Herculēs form the Keystone asterism, the broad torso of the hero.
M13 can be seen ​2⁄3 of the way, north (by west) from Zeta to Eta Herculis.
Although only telescopes with great light-gathering capability fully resolve the stars of the cluster, M13 can be visible to the naked eye depending on circumstances. With a low-power telescope,
Messier 13 looks like a comet or fuzzy patch. The cluster is visible throughout the year from latitudes greater than 36 degrees north, with the longest visibility during Northern Hemisphere spring and summer.

It is located at right ascension 16h 41.7m, declination +36° 28'. With an apparent magnitude of 5.8, it is barely visible with the naked eye on clear nights. Its diameter is about 23 arcminutes and it is
readily viewable in small telescopes. Nearby is NGC 6207, a 12th-magnitude edge-on galaxy that lies 28 arcminutes
directly northeast. A small galaxy, IC 4617, lies halfway between NGC 6207 and M13, north-northeast of the large globular cluster's center.

In traditional binoculars, the Hercules Globular Cluster appears as a round patch of light.
At least a 100mm telescope aperture will allow resolving the stars in M13's outer extents as small pinpoints of light. However, only larger telescopes allow resolving stars further into the center of the cluster.