A towering figure in the development of jazz, as well as one of the most beloved entertainers of the 20th century, Louis Armstrong was a trumpeter and vocalist whose unique playing changed the focus of the genre from a collective sound to one built around individual solos. His singing, too, wielded enormous influence on the vocal delivery of pop and jazz vocalists through his phrasing, enunciation and forays into scat singing. His naturally warm and gravely voice also made him an ideal interpreter of standards, which spurred his transition from jazz to the mainstream in the late 1940s and early 1950s. In doing so, Satchmo - as he was known to fellow musicians - became among the first African-American artists to cross over into mainstream white entertainment, where he continued to enjoy incredible success as a vocalist, most notably with his 1964 rendition of "Hello, Dolly!" which bounced the Beatles from the top of the pop charts. A tireless performer and benevolent soul who broadcast his personality and talents like a beacon across the globe, Louis Armstrong was unquestionably one of the defining artists in the history of popular music.