The noodles are usually up to one centimeter in size and are shaped like the letters A-Z and, more rarely, the numbers 0-9 or the @ sign.

As early as 1877, Paris grocers sold "...small bits of macaroni, for use in soup, which are stamped with... the letters of the alphabet.

"[2] and Paris restaurants served "...delicious soups made of macaroni or vermicelli cut up into the shape of letters of the alphabet..."[3] In 1883, The Chicago Herald Cooking School cookbook provided a recipe for soup calling for a small pasta such as "alphabet pastes of the same material as macaroni stamped in letters".

[5] Also unclear is whether the soup or the linguistic term for an overabundance of acronyms or abbreviations came first; food historian Janet Clarkson notes that "the first reference I have found so far to the metaphorical alphabet soup also occurs in 1883, in a quotation by the originator of Life magazine, John Ames Mitchell, referring to teaching his son the alphabet soup (the ABCs) of business.

[6] A similar product, Alphabetti Spaghetti, was sold by the H. J. Heinz Company for 60 years before being discontinued in 1990.