Popular big bands of the decade included Glenn Miller, Artie Shaw, The Dorsey Brothers and Count Basie. Big bands typically played swing music and featured a band leader along with 10 to 20 musicians.
In the early to mid-'40s bebop was at the forefront of the jazz scene. Popular artists included Charlie Parker and Thelonius Monk. Bebop featured complex harmony and chord changes along with the use of dissonance and syncopation.
Cool jazz followed bebop in the later part of the decade. Miles Davis' album, "Birth of The Cool," brought about a softer and smoother sound.
The music of the 1940s can be seen as the precursor to 1950s rock 'n' roll. Boogie woogie blues and bebop jazz gained popularity in the 1940s and were a big influence on the rock 'n' roll music of the 1950s.
1940s music--particularly the mid-'40s--can be characterized as "fun." Swing, bebop and pop music were attempting to be upbeat to counteract the stress of World War II.