Bass is a name shared by many different species of popular gamefish. The term encompasses both freshwater and marine species. All belong to the large order Perciformes, or perch-like fishes, and in fact the word bass comes from Middle English bars, meaning "perch." The collective name for a group of bass is a shoal.

* The temperate basses, such as the striped bass (Morone saxatilis) and white bass (M. chrysops), belonging to the family Moronidae.
* The black basses, such as the largemouth bass (Micropterus salmoides), smallmouth bass (M. dolomieu), spotted bass (M. punctulatus), and Guadalupe bass (M. treculii), belonging to the sunfish family, Centrarchidae.

The black basses are sometimes erroneously called black trout, but the name trout more correctly refers to certain members of the salmon family.

The black basses are distributed throughout a large area east of the Rocky Mountains in North America, from the Hudson Bay basin in Canada to northeastern Mexico. They live in California too. Several species, notably the largemouth and smallmouth basses, have been very widely introduced throughout the world, and are now considered cosmopolitan. Black bass of all species are highly sought-after game fish and bass fishing is an extremely popular sport throughout the bass's native range. These fish are well known as strong fighters, and their meat is eaten, being quite edible and firm, though catch-and-release fishing is becoming more popular in order to preserve fish populations.

All Micropterus species have a dull-green base colouring with dark patterns on the sides. Most reach a maximum overall length of 40–60 cm (16–24 in), but some strains of the largemouth have been reported to grow to almost a full metre (just over three feet) in length.

The male builds a "bed"(nest) in which a female is induced to deposit her eggs and then fertilizes them. The male continues to guard the eggs and fry until they disperse from the nest.

In Japan, to which the black basses are not native, there have been frequent attempts to eradicate various species of the fish.