What is "tressette"

Tressette or Tresette (trešeta in Croatian and Montenegrin) is one of Italy's major national trick-taking card games, together with Scopa and Briscola. It is recorded only from the early 18th century, though greater antiquity is suggested by its trumplessness. The name of the game, literally "three Seven" may refer to seven sets of three or four point possibilities when a minimum of three each (three, two, ace or all of those together in a matching suit are dealt), or to the fact that it is played up to twenty-one. There are many variants depending on the region of Italy the game is played in.