Gemini is a Zodiacal constellation otherwise known as the Twins. It is one of the 48 Greek constellations originally described by the 2nd century astronomer Claudius Ptolemy (Wikipedia). Gemini remains one of the 88 modern constellations defined by the International Astronomical Union (Wikipedia).
Gemini (abbrev. = Gem; genitive = Geminorum) covers 514 square degrees or 1.25% of the celestial sphere making it the 30th largest constellation. It contains 119 stars brighter than apparent magnitude 6.5, the brightest star being Pollux (Beta Geminorum). See Gemini for a photo this constellation from Bifrost Observatory.