Dicing is a knife technique for cutting ingredients, usually vegetables or fruits, into small, uniform cubes by making one set of parallel cuts and a second set at a right angle to the first. A standard dice runs about 1/4 to 1/2 inch; larger cuts are called "large dice" and smaller ones "fine dice" or "brunoise" (about 1/8 inch).
Dicing is distinct from julienne (thin, matchstick-shaped strips) and from brunoise, which is simply a finer dice rather than a different shape. "Macédoine" is sometimes used loosely as a size term, but properly refers to a mixture of diced fruits or vegetables rather than a specific cut size.
Because diced ingredients cook and season evenly, dicing is common in soups, stews, and sauces, and useful as a garnish or topping. A sharp chef's knife and stable cutting technique are essential for clean, consistent cuts; a mandoline can speed up high-volume prep.