Shortbread is so named because of its crumbly texture (from an old meaning of the word short). The cause of this texture is its high fat content, provided by the butter. The short or crumbly texture is a result of the fact that the fat inhibits the formation of long protein (gluten) strands. The related word "shortening" refers to any fat that may be added to produce a short (crumbly) texture.

Shortbread is different from shortcake, which can be similar to shortbread, but which can be made using vegetable fat instead of butter and always uses a chemical leavening agent such as baking powder, which gives it a different texture.

Shortbread biscuits are often associated with normal egg-based biscuits, but they hold their shape under pressure, making them ideal for packed meals.

Shortbread is baked at a low temperature to avoid browning. When cooked, it is nearly white, or a light golden brown. It may be sprinkled with more sugar while cooling. It may even be crumbly before cooled, but will become firmer after cooling.

Shortbread is traditionally formed into one of three shapes: one large circle, which is divided into segments as soon as it is taken out of the oven (petticoat tails, named from the French petits cotés, a pointed biscuit eaten with wine); individual round biscuits (shortbread rounds); or a thick (¾" or 2 cm) oblong slab cut into fingers.

The stiff dough retains its shape well during cooking. The biscuits are often patterned, usually with the tines of a fork before cooking or with a springerle-type cookie mold. Shortbread is also sometimes shaped in hearts and other shapes for special occasions. The classic Girl Scout cookie "Trefoils" are shortbread in the shape of the Girl Scout trefoil logo.

Shortbread is generally associated with and originated in Scotland, but due to its popularity it is also made in the remainder of the United Kingdom, and other countries like Denmark, Ireland and Sweden. In the latter a popular recipe of it is called drömmar, literally meaning dreams. The Scottish version is the best-known, and Walkers Shortbread Ltd is Scotland's largest food exporter.

Shortbread was chosen as the United Kingdom's representative for Café Europe during the 2006 Austrian presidency of the European Union.

Scottish chef John Quigley, of Glasgow's Red Onion, describes shortbread as "the jewel in the crown" of Scottish baking.