The simplest variations are made through substitution or addition. By this I mean substituting a portion of the white bread flour for another, such as whole wheat or rye, or by adding additional ingredients, such as cheese, herbs, or even chili peppers. There's also the option of using the basic dough as a sort of medium for other ingredients, such as pizza, focaccia, and calzone. More abstract variations on the basic recipe lies not only in its ingredients but also in the method in which it's made, such as bagels and soft pretzels, which employs a much "tighter" dough and are boiled before they are baked. And one of the most fundamental cooking methods for bread is done not in an oven but in a skillet, such is the case of English muffins, which are also based on a variation of the basic bread recipe.
The interesting thing is that making these variations makes bread baking not only exciting and flavorful, it also makes you look like a master baker to friends and relatives. Once you've gained the understanding of basic yeast bread it's only a small quantum leap to seemingly endless variations, but others will assume you've an internal tome of recipes. And all the while it's simply a variation on a theme. After some time a written recipe will no longer be required; your breads will be made using your own intuition.
Thus said, being the culinary history geek that I am, I compulsively have to mention some background on recipes included in this section, because when armed with that knowledge, and knowing that you are making these recipes pretty close to the original makes it even more enjoyable (at least to me it does).
Pizza, for example, which happens to be one of my personal favorites, was originally nothing more than Mediterranean flatbread with a topping of salt, herbs, and olive oil. Its originators were Greek, and some say that its name is even derived from the Greek word pitta. When pizza found its way to Italy it was seasoned and baked in this same fashion. Tomatoes, a product of the Americas, weren't available in Europe until the 16th century. Pizza at the time was simply seasoned flatbread: focaccia. Pizza Margherita is probably one of the first to resemble the pizzas of today. A cook named Raffaele Esposito, who was catering a party for Queen Margherita di Savoia, first made it in 1889. Passionate about his homeland he used his pizza to pay homage to Italy's flag: red (tomato), white (mozzarella) and green (basil).
What I'm going to state next will probably question my credibility with some, if not infuriate others, but here goes: the main difference between a soft pretzel and a bagel are their shape; both are made using high gluten flour, which yields a tough and chewy dough, both are boiled before being baked (poached, actually), and both originated in Eastern Europe. In fact the first bagels are said to have been made by a pretzel baker in Vienna in the 1600's. Apparently he made them in honor of King John III Sobieski of Poland for saving the city from invading Turks. To honor the King's skill as a horseman the anonymous baker used pretzel dough to make a sort of roll in the shape of a stirrup; the Austrian word for stirrup is beugel. And the pretzel supposedly dates back to the fifth or sixth century AD. The original name for pretzel was pretiola, which translated to "little reward;" the pretzel's shape was intended to represent children's arms folded in prayer and were sometimes given to children as a little reward upon completing their daily prayers.
Whether these are actually true or simply folklore is difficult to say, but I'm a sucker for a good story. And when I feel the dough between my fingers it really does make me think, it makes me think about the simplicity of the dough, and also the complexity of how such a few simple ingredients are entwined into daily life, both past and present.