The twenties was a time of mostly "hot jazz," so named because it was so kinetic that it actually produced heat. Many of the great players of the day had to play their instruments wearing oven mitts and some form of protective clothing. Early jazz patrons often brought uncooked meals with them to jazz concerts, using the heat from the stage to prepare their food during the course of the show. In those days, when someone said that a particular performance was "cooking," they weren't just whistling Dixie.
By the end of the twenties, jazz was firmly ensconced (ensconced?) in the American consciousness. Jazz bands criss-crossed the country, bringing the music to ever-smaller and more remote places. Jazz record labels sprung up all over the place, bringing the music to places smaller and more remote still. Thus, it is estimated that by 1934, the only person in America who had not yet heard jazz was Mr. Zebulon Creasey, of Dog Pike, Kentucky. What is ironic is that Mr. Creasey's home had once been personally visited by the Paul Whiteman Band, featuring the great Bix Biederbecke, but he was visiting his sister in West Virginia at the time and missed them. They played instead for his brother, Whistler (so named because he had once painted his mother), who was so inspired, he left immediately for New York and later played trombone for Fletcher Henderson. To this day, he is considered the finest hillbilly jazz musician of his era.
The thirties brought an increasing sophistication to jazz. With the emergence of the great Duke Ellington, whose visionary compositions gave the first glimpses of how complete jazz could truly be as an American art form, jazz began to take its place in the collective culture. And for the first time, the music began to appeal to Americans of all heights (jazz had previously been considered "unseemly" for people under 5'4").
The thirties also brought about the era of the great jazz venues, such as the Savoy Ballroom and the legendary Cotton Club (so named because the price of admission was actually cotton, or a textile product of some sort. This practice died out with the advent of synthetic fabrics, which had little value to the fashion-conscious mobsters who ran the joint). These venues acted as the proving ground for virtuoso musicians, the incubators in which bold and exciting new directions in jazz were first born, and among the first places in America you could call someone a "hep cat" with a straight face.
Moving into the forties on the strength of sheer momentum alone, we find ourselves firmly in the midst of the swing craze. Whether or not you consider swing an official school of jazz, or just "jazzified" popular music, you have to admit that without the emergence of big band, virtually every high school in America today would be without a jazz ensemble.
Of course, we shouldn't dismiss big band music out of hand. There was some great music produced during the swing era, and some great musicians. It was also just about the only time in history that teenage girls got hysterical about jazz musicians. No one who has played jazz since has been able to escape that wistful fantasy of Beatle-esque clouds of screaming girls going out of their minds for a particularly swinging rendition of Well You Needn't.
By the end of the forties, big band musicians tired of playing the same strict charts night after night were getting together after hours and experimenting with different directions. Musicians like Dizzy Gillespie, Charlie Parker, and Thelonious Monk were exploding the traditional definitions of jazz with breakneck chord changes, unique scales, and some of the coolest hats in music history. Calling the new form "Be-bop" (and you'd think I'd have a decent gag for that, but here we are), these giants ushered jazz into the fifties and arguably, into its golden age.
With the advent of Be-bop, jazz took on an intricacy and intellectual challenge heretofore only seen in pedantic articles that used the word "heretofore" for no good reason. As swing music gave way to homogenized popular music, and then to rock and roll, jazz became increasingly introspective and less concerned with popular tastes. Jazz musicians themselves began to embody an aloof and supremely self-confident attitude that would become known as "cool." This is not to be confused with so-called "cool jazz," which was an entity unto itself, or Kool-Aid, which has nothing at all to do with jazz so forget I even mentioned it.
At any rate.