Finch is a general term popularly applied to more than 1,000 species of stout-billed, seed-eating birds that are classified in several different families and subfamilies. Among the weaverbirds, Ploceidae, for instance, are many species called finches. The WAXBILLS, Estrildidae, are also a type of finch. Charles Darwin based much of his theory of evolution on birds now known as DARWIN'S FINCHES (Geospizidae). In a more restricted sense, however, finches belong primarily to the subfamily Carduelinae of the great family Fringillidae, which also includes the cardinals, buntings, grosbeaks, towhees, sparrows, and many other birds. Other carduelines, which are not specifically named finch, include the siskins, redpolls, crossbills, and pine grosbeaks.

Most finches, regardless of their classification, are primarily seedeaters, with stout bills and a well-developed gizzard. But even the seedeaters usually feed their young, for a few days at least, on more easily digested insects. Exceptions occur among the goldfinches, redpolls, and some other carduelines. Goldfinches, for instance, delay nesting until new thistledown is available for building their compact, waterproof nests and until the softer, pulpier new seeds of the year are available for feeding their young. Then the young are fed by regurgitation of partially digested seeds.

Many finches are brightly colored with red, yellow, or blue predominating, as in the purple (royal red) finch, goldfinch, and indigo bunting. The painted bunting is an extreme example of bizarre coloration, sporting a breathtaking combination of red, blue, green, and yellow. Most finches are very musical, with songs that vary from the soft twittering of goldfinches and canaries to the spirited warble of the purple finches in flight. Many authorities consider finches the highest and latest development on the avian evolutionary ladder.