Louis Armstrong was an American trumpeter, singer, and composer who became one of the most influential figures in jazz. Rising to fame in the 1920s, he revolutionized the genre with his virtuosic trumpet playing, distinctive gravelly voice, and charismatic stage presence. His innovations in improvisation and phrasing helped shape modern jazz and popular music. Iconic songs like "What a Wonderful World" and "Hello, Dolly!" cemented his legacy as a beloved cultural icon worldwide.