Louis Armstrong, nicknamed Satchmo and Pops, was an American jazz trumpeter and singer.Armstrong was a charismatic, innovative performer whose improvised soloing was the main influence for a fundamental change in jazz, shifting its focus from collective improvisation to the solo player and improvised soloing. One of the most famous jazz musicians of the 20th century, he was first known as a cornet player, then as a trumpet player, and toward the end of his career he was best known as a vocalist and became one of the most influential jazz singers..