http://www.billspianopages.com/how-to-really

Stride is a really useful technique if you're starting to learn jazz piano. It's particularly associated with early jazz styles from the early twentieth century, but it's so incredibly flexible you can use it with a variety of styles, from blues piano to cocktail.

Stride gets its name from what's going on in the pianists' left hand: by alternating a single low note a couple of octaves or so below middle C with a block chord closer to the middle of the piano, you create a rhythmic, driving style that, in effect, mimics a rhythm section.

I use some very basic jazz chord extensions in this tutorial, like sixths, sevenths and ninths, so it's worth being familiar with chords, and especially how they're used in a jazz piano context. In particular, if you're new to playing stride, work very hard on the left hand first - it's important that it's very precise, with few bum notes, and that you maintain a regular, steady tempo.

In the right I'm taking advantage of one of the piano's most important characteristics - it's very easy to play chords. In this sort of style of piano playing, you can save yourself a lot of mental effort by avoiding melodic, scale-based improvisation, and basing all your improvisation around chord shapes, creating interest by varying the rhythm and attack - treating the piano, at times, as if it were a percussion instrument as well as one designed for melody and harmony.