The song sparrow (Melospiza melodia) is a medium-sized New World sparrow. Among the native sparrows in North America, it is easily one of the most abundant, variable and adaptable species.

Adult song sparrows have brown upperparts with dark streaks on the back and are white underneath with dark streaking and a dark brown spot in the middle of the breast. They have a brown cap and a long brown rounded tail. Their face is gray with a brown streak through each eye. They are highly variable in size across numerous subspecies. The average body mass of all races is 32 g but the widespread nominate subspecies weighs only about 22 g on average. The maximum lifespan in the wild is 11.3 years. The eggs of the song sparrow are brown with greenish-white spots. Females lay three to five eggs per clutch, with an average incubation time of 13–15 days before hatching.

In the field, they are most easily confused with the Lincoln's sparrow and the Savannah sparrow. The former can be recognized by its shorter, grayer tail and the differently-patterned head, the brown cheeks forming a clear-cut angular patch. The Savannah sparrow has a forked tail and yellowish flecks on the face when seen up close.

Though a habitat generalist, the song sparrow favors brushland and marshes, including salt marshes across most of Canada and the United States. They also thrive in human dominated areas such as in suburbs, agricultural fields, and along roadsides. Permanent residents of the southern half of their range, northern populations of the song sparrow migrate to the southern United States or Mexico during winter and intermingle with the native, non-migratory population. The song sparrow is a very rare vagrant to western Europe, with a few recorded in Great Britain and Norway.

These birds forage on the ground, in shrubs or in very shallow water. They mainly eat insects and seeds. Birds in salt marshes may also eat small crustaceans. They nest either in a sheltered location on the ground or in trees or shrubs. Song sparrows with areas of shrub cover in their territory, away from the intertidal coastline, have greater over-winter survival, as well higher reproductive success.

The sparrow species derives its name from its colorful repertoire of songs. Enthusiasts report that one of the songs heard often in suburban locations closely resembles the opening four notes of Ludwig van Beethoven's Symphony No. 5.