From Citizendium, the Citizens' Compendium
Stride piano is a solo jazz piano style. The name comes from the way the left hand 'strides' between a bass note on the upbeats and a chord on the downbeats. (The first and third beats of a four-beat measure are the upbeats and the second and fourth beats are the downbeats.) This is the same beat that ragtime used; however, stride pianists used a wide range of other techniques in the left hand: arpeggios, walking bass, and boogie-woogie. Also unlike ragtime, the left-hand frequently swung or otherwise strayed from the beat. In ragtime, only the right-hand would deviate from the beat.
As with most solo piano, the right hand plays melody, dipping occasionally into harmony.
The greatest stride pianists were James P. Johnson (1894–1955), Fats Waller (1904-1943), and Willie "The Lion" Smith (1897-1973).
James P. Johnson is best-known today as the author of Charleston, a tune he composed as part of a Broadway show. Johnson had learned classical piano, and he was a student of Scott Joplin's rags. Johnson is sometimes described as "The Father of Stride". In jazz, based on improvisational live performance, it is impossible to precisely assign paternity. Johnson's Carolina Shout, published in 1920, is considered the first stride piano piece ever published.
Fats Waller was Johnson's protege. The composer of Ain't Misbehavin, Waller performed and recorded prolifically with small groups; but he also performed a number of solo stride pieces. Like Louis Armstrong and Louis Jordan, Waller was a charismatic performer whose stage persona overshadowed his undeniable talents.
Willie "The Lion" Smith, nee Henry Joseph Bonaparte Bertholoff, is the only known stride pianist who was also a cantor in a synagogue. Smith is less-well known as a composer than Waller or Johnson. He was drawn to classical music, and in the highly competitive world of Harlem jazz piano--where you took a player's chair by playing faster and swinging harder, he showed a rare willingness to play Debussy-like passages.