A baguette is a specific shape of bread, commonly made from basic lean dough, a simple guideline set down by French law, distinguishable by its length, very crisp crust, and slits cut into it to enable proper expansion of gasses and thus formation of the crumb, the inner soft part of bread.
The standard diameter of a baguette is approximately 5 or 6 cm, but the bread itself can be up to a meter in length, though usually about 60cm. A Parisian baguette typically weighs 250 grams (8.8 oz), but this is not legally regulated and varies by region.
It is also known in English as a French stick or a French bread.
The "baguette" is sometimes said to be a descendant of the pain viennois, bread first developed in Vienna, Austria in the mid-19th century when deck ovens, or steam ovens, were first brought into common use. Deck/steam ovens are a combination of a gas-fired traditional oven and a brick oven, a thick "deck" of stone or firebrick heated by natural gas instead of wood.
The first such oven was brought (in the early nineteenth century) to Paris by the Austrian officer August Zang, whom some French sources thus credit with originating the (probably twentieth century) baguette. Deck ovens use steam injection, through various methods, to create the proper baguette. The oven is typically well over 205 °C (400 °F), the steam allows the crust to expand before setting, thus creating a lighter, more airy loaf.