The "Old World Warblers", family Sylviidae - although sylviid warblers or true warblers may be more appropriate -, are a family of small passerine bird species. The Sylviidae mainly occur as breeding species, as the name implies, in Europe, Asia and, to a lesser extent Africa. However, most birds of temperate regions are strongly migratory, and winter in the latter continent or tropical Asia. Most are of generally undistinguished appearance, though some Asian species are boldly marked. The sexes are often identical, but may be well distinct e.g. in Sylvia. Many are accomplished songbirds, though perhaps not as much as other warblers or some thrushes.
The American wood warblers (Parulidae), the Olive Warbler (Peucedramidae) and the stenostirid warblers or "flycatcher tits" (Stenostiridae) are not closely related to the sylviids. The Australian warblers (Acanthizidae), apart from also being Passeri, are entirely unrelated.