c. 1840: Adolphe Sax, a Belgian, invents the saxophone.

1902: The 12-year-old Jelly Roll Morton "invents" jazz, or so he later claims. A habitue of Storyville, the red-light district of New Orleans, Morton combines ragtime, French quadrilles and the hot blues played by Buddy Bolden, the notoriously hard-living cornetist.

1917: The Original Dixieland Jazz Band, a white group, makes the first jazz recording, "Livery Stable Blues." It sells a million copies, launching jazz as popular music. Freddie Keppard, a black band leader, had rejected the chance to make the first jazz record - he was afraid other musicians would copy his style.

1925-1928: Take it away, Satchmo: With his Hot Fives and Hot Sevens recordings, Louis Armstrong revolutionizes the jazz form, encouraging solo improvisation over ensemble playing.

1929-1945: The swing era rises and falls. Duke Ellington, Jimmie Lunceford and Count Basie lead influential groups. Most of the big hits, though, are recorded by white band leaders like Glenn Miller, Benny Goodman and Tommy Dorsey.

c. 1935-1955: The jam session as art form: West 52d Street in Manhattan, packed with clubs, becomes the playground for Charlie Parker, Dizzy Gillespie, Miles Davis, Thelonious Monk and all their friends.

1936: Well before the rest of the country, jazz becomes integrated. At the Congress Hotel in Chicago, Lionel Hampton and Teddy Wilson sit in with Benny Goodman's ensemble. Two years later, Billie Holiday joins Artie Shaw's big band.

1939: While playing "Cherokee" during a Harlem jam session, Charlie Parker happens upon a harmonic discovery that leads to be-bop, a far more intricate style of jazz, both harmonically and rhythmically.

1943: Jazz ascends to the concert hall: The first of Duke Ellington's annual Carnegie Hall programs and the premiere of "Black, Brown and Beige," his influential long-form work about the history of American blacks.

1951: On the heels of Miles Davis's "Birth of the Cool," musicians like Chet Baker and Gerry Mulligan form the so-called cool school, turning down the volume and intensity. It happens, of course, in California.

1951: Sidney Bechet relocates to Paris, the first of many American jazz expatriates including Kenny Clarke, Arthur Taylor and Bud Powell. Racial tension was less pronounced and European audiences were far more appreciative.

1954: Jazz goes outdoors: George Wein, a pianist and singer, rewrites his jazz resume by inviting musicians to Newport, R.I., for the first of many Jazz Festivals.

1956: A crossover dream: Ella Fitzgerald makes the first of several "Songbook" recordings for Verve, the impresario Norman Granz's new label. The Songbooks make Fitzgerald an international star.

1959: A pivotal year, with several records that expand the very possibilities of improvisation: Miles Davis's "Kind of Blue," John Coltrane's "Giant Steps," Ornette Coleman's "Shape of Jazz to Come."

1964: The avant-garde gains mainstream recognition as Thelonious Monk makes the cover of Time magazine, which christens him the high priest of be-bop.

1969: Miles Davis's "Bitches Brew," a primordial jazz-rock fusion record, sells 500,000 copies, turning many rock fans on to jazz but leaving some hard-core Miles followers groaning.

1972-1977: New York's "loft jazz" scene blooms, with experimental, post-bop players performing in lofts like Ali's Alley. Among the players on the scene are Joe Lovano and David Murray.

1979: On Jan. 5, the famously cosmic Charles Mingus dies in Cuernavaca, Mexico, at the age of 56. That same day, 56 whales beach themselves on the Mexican coast.

1984: The new generation gets a leader who looks backward: Wynton Marsalis, at 22, wins a Grammy for his "neo-bop" record "Think of One." The same night, he takes a classical Grammy for his recording of trumpet concertos.

1989-1991: Frontmen and backlash: Trying to duplicate Marsalis's commercial success, record labels snap up straight-ahead players like Roy Hargrove, Antonio Hart and Christopher Hollyday. Much grumbling ensues from those who consider these so-called Young Lions too imitative or too green.

1991: Jazz as institution: Marsalis is appointed artistic director of the new Jazz at Lincoln Center program. Big audiences but big detractors, too, who claim that Marsalis is anti-modernist and anti-white.

1992: A new fusion trip: The British "acid jazz" group Us3, which blends hip-hop and electronic samples of jazz cuts, gets permission to raid the Blue Note archives. Meanwhile, in Brooklyn, the hip-hop group Digable Planets records "Rebirth of Slick (Cool like Dat)," built around the sampled horn lines of James Williams's "Stretchin.' " Suddenly, a new degree of jazz cool.

1993: Jazzmen can be pop stars, too: Joshua Redman, the Harvard summa cum laude saxophonist, chooses jazz over Yale Law and releases two records. Critics love the records and fans love Redman: in concert, young women shriek and young men pump their fists in the air.