Focaccia means many things in Italy.
In Massa, on the Tuscan coast, a focaccia ordered in a pizzeria a close cousin of pizza, a disk of dough the pizzaiolo bakes untopped (or, at the most, with slices of fresh tomato laid over it). It emerges crisp and puffy, and is finished with fresh toppings, for example good, fresh buffalo mozzarella and slices of prosciutto, or perhaps shredded arugula and fresh tomatoes with bresaola (salt-cured beef).
But in much of Tuscany, what you'll be given if you ask for focaccia in a bakery is what's called schiacciata (meaning: "flattened") in Florence: a thin loaf of dough that was tamped down with a spoon to dimple its surface, sprinkled with salt, and well oiled with extra-virgin olive oil before baking. A heavenly snack, and the perfect base for a sandwich made with prosciutto or mortadella and cheese (or whatever else suits your fancy). This is known as "pizza bianca" in the Rome/Lazio area.
You can find this kind of focaccia in the nearby Liguria region as well, but they also make others; I'll never forget the time I dined at Manuelina's in Recco (not far from Portofino) and beheld a focaccia the size of a wagon wheel, filled with melted cheese whose slight bitterness interacted marvelously with the saltiness of the bread. They served it as an antipasto, and after the first bite, I was sorely tempted to tell the waiter to forget about the other delicacies I'd ordered and just bring me more.
The basic focaccia recipe below will work nicely as a daily bread alternative, while the more elaborate focaccias will work well as party or snack foods. As will the focaccia al formaggio, which also makes for a fine antipasto, or as the main dish for a light lunch (served with a tossed green salad, seasoned with olive oil, vinegar, and salt, for example).
Ligurian-style Focaccia Recipes:
The basic Ligurian-style recipe.
Focaccia con la Salvia
A close cousin of the above, delicately flavored with sage.
Focaccia col Formaggio
Cheese-filled focaccia is a stunning treat.
Focaccia con le Cipolle
Focaccia topped with onions, the traditional sendoff of the Ligurian sailor.
A Few Non-ligurian Focaccia Recipes
Quick and tasty -- excellent as an antipasto, and easy enough for children to make too.
Focaccia and Toppings:
Easy, tasty topping ideas.
Tasty little Puglia-style focaccias stuffed with ricotta (and whatever else suits your fancy).
On the grill
Bread (including focaccia) can be baked on the grill too, and here's some advice for that method.
[Edited by Danette St. Onge on 1/31/2016]