A junco, genus Junco, is a small North American bird in the New World sparrow family Passerellidae. Junco systematics are still confusing after decades of research, with various authors accepting between three and twelve species. Despite having a name that appears to derive from the Spanish term for the plant genus Juncus (rushes), these birds are seldom found among rush plants, which prefer wet ground, while juncos prefer dry soil.

New World sparrows are a group of mainly New World passerine birds, forming the family Passerellidae. They are seed-eating birds with conical bills, brown or gray in color, and many species have distinctive head patterns.