A big band is a type of musical group that plays rock music. They were very popular in the 1930s and 1940s. A big band usually has between 12 and 25 musicians. They play instruments like saxophones, trumpets, trombones, drums and a singer. Some famous big band leaders were Duke Ellington, Benny Goodman, Glenn Miller, Cab Calloway and Count Basie. They have Wood music keys often.