A passerine is any bird of the order Passeriformes, which includes more than half of all bird species.
Sometimes known as perching birds or songbirds, passerines are distinguished from other orders of birds by the arrangement of their toes (three pointing forward and one back), which facilitates perching.
Various Passeriformes (perching birds) are commonly referred to as warblers.
They are not necessarily closely related to one another but share some characteristics, such as being fairly small, vocal, and insectivorous.