The general word for a cured, ready-to-eat sausage. The English word 'salami' is actually the plural, for what in Italy is called a salame.
In Italy, the reigning salame can change from one village to the next. They come in all shapes and sizes, although almost all are made of chopped or ground pork meat and fat, with spices (unless they are desserts that resemble a salame, such as the salame del re).
Regional varieties are endless. Every Alpine valley seems to have its own; salametto from Piedmont is one of many that is a mix of pork and pancetta. Some of the most renowned salami come from Emilia-Romagna, including the king of salami, culatello, made from the offcuts of Parma ham, as well as strolghino and the garlic sausages of Ferrara (salame all'aglio and salame gentile). In Umbria, the town of Norcia has been famous for meats since Roman times.
Some salami are smoked, like the popular salame Napoli. Some are soft and spreadable, such as the salama al sugo of Ferrara and the spicy 'nduja of Calabria. Sicily is a great salame region, with versions made from the suino nero (black pig) of the Nebrodi Mountains, salami flavoured with fennel or pistachios, and boar salame from Ragusa.
Some salami appear under other names, such as sopressata or sopressa, ciascuino, mortandela, ciuga, saggicciotto, etc; Bologna's famous mortadella is a salame too.
One salame you won't see in Italy—on a pizza or anywhere else—is pepperoni. That's strictly Italian-American, though related to the salsiccia piccante or salamino piccante of Naples and other similar products.
A number of salame are in the Ark of Taste, including the aforementioned salama al sugo and 'njuga, plus:
salame con lengual: a pure pork salame of Mantua (Lombardy) using a pig's tongue cured in spices
salame d'asino: the donkey salame of Vicenza (Veneto)
salame di cinghiale: boar salame, celebrated in an April sagra in little Val del Torre (Piedmont)
salame di Fabriano: high quality salame made from ham in the Marche
salame di Milano: crespone
salame Napoli: a smoked salame of lean pork, lean beef and pork fat mixed with salt, pepper, chili pepper and crushed garlic cooked in wine
salame di Sant'Angelo di Brolo: fragrant bright red sausage made in the eponymous town in Sicily of pigs raised on acorns and beans
salame di Tergu: a simple lean pork meat salame of Sardinia, seasoned only with salt and pepper
salame ungherese: spicy Hungarian salami
salame delle Valli Tortonesi: aged in a special microclimate, with very little salt (Piedmont).