Cancer
Cancer is a Zodiacal constellation otherwise known as the Crab. It is one of the 48 Greek constellations originally described by the 2nd century astronomer Claudius Ptolemy (Wikipedia). Cancer remains one of the 88 modern constellations defined by the International Astronomical Union (Wikipedia).
Cancer (abbrev. = Cnc; genitive = Cancri) covers 506 square degrees or 1.23% of the celestial sphere making it the 31st largest constellation. It contains 104 stars brighter than apparent magnitude 6.5, the brightest star being Tarf. See Cancer for a photo this constellation from Bifrost Observatory.
For more information see the entries for Cancer at Wikipedia and U. Wisconsin. For a chart of Cancer, see Cnc (IAU).