Eleanora Fagan (April 7, 1915 – July 17, 1959), known professionally as Billie Holiday, was an American jazz and swing music singer. Nicknamed "Lady Day" by her friend and music partner Lester Young, Holiday had an innovative influence on jazz music and pop singing. Her vocal style, strongly inspired by jazz instrumentalists, pioneered a new way of manipulating phrasing and tempo. She was known for her vocal delivery and improvisational skills.