The wire-tailed swallow (Hirundo smithii) is a small passerine bird in the swallow family. It has two subspecies: H. s. smithii, which occurs throughout Africa, and H. s. filifera, which is found in southern and southeastern Asia. It is mainly resident, but populations in Pakistan and northern India migrate further south in winter. The genus name Hirundo is the Latin word for swallow. The species name smithii commemorates Christen Smith, a Norwegian botanist and geologist.
The wire-tailed swallow is a small swallow, measuring 18 cm in length. It has bright blue upperparts, bright white underparts and a chestnut cap. Immature birds lack tail wires, and have dull brown (rather than chestnut) caps. The species is named for the very long filamentous outermost tail feathers, which trail behind like two wires. The sexes are similar in appearance, but the female has shorter "wires". Juveniles have a brown crown, back and tail. The Asian form, H. s. filifera, is larger and longer-tailed than the abundant African H. s. smithii.