Primarily what is known as Harlem stride piano.

Stride and Noveltty piano were developed from the Ragtime. That was about1920. Stride piano came up in Harlem, NY where black pianists, which hadn`t a musical graduation, began to improvise the Rags and so created an own style. Novelty piano developed about the same time in Chicago where only white pianist, which had a highly musical graduation and which were influenced by the european music-styles began to create their own style. Stride and Novelty piano sound very similar so they can be called the first Jazz-styles.

True.

A new way of playing the piano called the Harlem Stride style.

Stride piano is a style of playing where the left hand plays an alternating pattern of low bass notes and middle register chords. The left hand is jumping around a lot so I guess that's where 'stride' comes from.