Louis Armstrong - 'Satchmo' was a musical pioneer on the trumpet. "He was the first guy to swing," said Dan Balmer, a Portland jazz guitarist and educator.
"Swing is an important concept to jazz, a kind of different rhythmic feeling we associate with jazz music," he added.
Armstrong, who gained prominence in the early '30s, also was one of the first jazz artists to improvise and the first to popularize jazz music.
He changed the way music, and especially jazz, is played.
The big bands - The Big Band Era in the 1930s and 1940s featured large ensembles that packed dance halls as jazz became America's popular music.
The groups usually had nearly 20 members, and arrangements often featured call and response between the sections, such as the saxophones playing a line, and the trumpets echoing back.
Performances also had solos, and the bands regularly had vocalists, as well.
Duke Ellington, Count Basie and Benny Goodman were among the most popular band leaders.
Charlie Parker and Dizzy Gillespie - 'Bird' on alto sax and 'Diz' on trumpet were the giants of be-bop, a style that flourished during the '40s and early '50s.
"Be-bop was a reaction to big band," said Margaret Mayer, director of instrumental music for Blue Mountain Community College.
The frenetic and aggressive music, played by small groups such as quartets and quintets, concentrated on the individual performers, giving them more freedom with lengthy solos.
"That's where jazz sort of lost its audience. It stopped being dance music," Balmer said. Fewer people could play it, and fewer people listened to the complex songs, he added.
Billie Holiday - 'Lady Day' was one of the greatest jazz singers, and a unique stylist whose phrasing was inspired by Louis Armstrong.
Holiday "elevated both superior and lame pop songs through her interpretations," according to the Smithsonian Collection of Classic Jazz. Her career lasted from the '30s to the '50s.
Like Charlie 'Yardbird' Parker, she fell into substance addiction and died early. To many, her near-tragic singing can't be separated from her stormy life.
Post bop - After be-bop, jazz went a number of directions at once, Balmer said.
Cool jazz, or West Coast Jazz, was a more relaxed music, as opposed to the 'hot' form that preceded it. Pianist Dave Brubeck ("Take Five") and trumpeter Miles Davis ("Birth of the Cool," "Kind of Blue") frequently are associated with cool jazz.
Musicians such as saxophonist Ornette Coleman also began seeking more freedom, and ignored the traditional chord progressions and scales that formed the basis for jazz. The resulting style was free jazz.
Fusion - In the '70s and '80s, jazz merged with other forms of music, such as pop, rhythm and blues, funk and even country and reggae. Fusion is commonly referred to as the mingling of jazz and rock, though. Davis and keyboardist Herbie Hancock, who still tours, were some of the style's most important forces.
Fusion was opposed by some artists, who felt it too commercial. Young lion Wynton Marsalis led a return to more traditional jazz in the '80s, and continues to be a prominent influence. "Jazz really split down the middle, the traditionalists and the non-traditionalists," Balmer said.
Jazz today - Jazz still is evolving, with some groups even using a DJ on the turntables. That said, there's a wide range of styles that today's jazz musicians play; everything from big band to bop to free jazz.
Information from Dan Balmer, Margare Mayer, and "The Smithsonian Collection of Classic Jazz."