Chianti is not a type of grape, but rather the region that this particular wine comes from, and the Chianti region of Italy is in Tuscany.
The primary grape used to make Chianti wine is called Sangiovese (san-jo-veh-zeh), and that's where Chianti's magical food pairing ability comes from.
Sangiovese is a thin skinned grape that ripens slowly. It produces a wine with as much acidity as Syrah, but with a lighter body. Sangiovese has a medium body similar to Tempranillo.
Sangiovese is Italy's most commonly planted red grape varietal, but for wine made with Sangiovese to be called Chianti, the wine must come from a specific region in Italy. Outside of the Chianti region, wine made from the Sangiovese grape goes by a variety of names, depending on where it is made, such as: Brunello, Vino Nobile di Montepulciano, Morellino, or just Sangiovese, which is what it goes by in Washington State.
Grab a bottle, any bottle, of Sangiovese, and pour yourself a glass.