The White wagtail is a slender bird with the characteristic long, constantly wagging tail of its genus. There are a number of other subspecies, some of which may have arisen because of partial geographical isolation, such as the resident British and Irish form, the pied wagtail M. a. yarrellii, which now also breeds in adjacent areas of the neighbouring European mainland. The Pied wagtail exchanges the grey colour of the nominate form with black (or very dark grey in females), but is otherwise identical in its behaviour. Other subspecies, the validity of some of which is questionable, differ in the colour of the wings, back, and head, or other features. Some rraces show sexual dimorphism during the breeding season. As many as six subspecies may be present in the wintering ground in India or Southeast Asia and here they can be difficult to distinguish.

The white wagtail (Motacilla alba) is a small passerine bird in the family Motacillidae, which also includes pipits and longclaws. The species breeds in the Palearctic zone in most of Europe and Asia and parts of North Africa; it also has a toehold in western Alaska as a scarce breeder. It is resident in the mildest parts of its range, but otherwise migrates to Africa. In total, there are between 9 and 11 subspecies of M. alba; in Ireland and Great Britain, the black-backed subspecies known as the pied wagtail (M. a. yarrellii) predominates.
The white wagtail is an insectivorous bird of open country, often near habitation and water. It prefers bare areas for feeding, where it can see and pursue its prey. In urban areas, it has adapted to foraging on paved areas such as car parks. It nests in crevices in stone walls and similar natural and human-made structures.
This species breeds throughout Eurasia up to latitudes 75°N, only being absent in the Arctic from areas where the July isotherm is less than 4 °C. It also breeds in the mountains of Morocco and western Alaska. It occupies a wide range of habitats, but is absent from deserts. White wagtails are residents in the milder parts of its range such as western Europe and the Mediterranean, but migratory in much of the rest of its range. Northern European breeders winter around the Mediterranean and in tropical and subtropical Africa, and Asiatic birds move to the Middle East, India, and Southeast Asia. Birds from the North American population also winter in tropical Asia.
It is the national bird of Latvia and has featured on the stamps of several countries. It is listed as being 'of least concern' by IUCN.