A
bright and
brassy jazz style typical of
the southern US, especially
New Orleans, in the first half of the
20th century.
Dixieland jazz is related to
ragtime, a somewhat earlier style.
Dixieland jazz is typically played by an ensemble including a banjo and lots of brass (a trombone and trumpet at the very least). Think of the jazzy versions of "When the Saints Go Marching In", a classic of Dixieland jazz, and you'll understand what Dixieland sounds like.