Phelsuma is a large genus of geckos in the family Gekkonidae. Species in the genus Phelsuma are commonly referred to as day geckos.

Gekkonidae is the largest family of geckos, containing over 950 described species in 62 genera. The Gekkonidae contain many of the most widespread gecko species, including house geckos (Hemidactylus), the tokay gecko (Gekko), day geckos (Phelsuma), the mourning gecko (Lepidodactylus), and dtellas (Gehyra). Gekkonid geckos occur globally and are particularly diverse in tropical areas. Many species of these geckos exhibit an adhering ability to surfaces through van der vaals forces utilizing intermolecular forces between molecules of their setae and molecules of the surface they are on.