Stride is a left-hand technique where you alternate between a low bass note (beats 1 and 3) and a mid-register chord cluster (beats 2 and 4). The hand literally strides up and down the keyboard. It creates a built-in bass line and rhythm section with just one hand.
Beat 1/3: root in octave 3. Beat 2/4: 3rd + 5th + 7th cluster in octave 3-4. The hand jumps between the two positions. Second variant uses the 5th as the bass note.
For solo piano where you need to provide your own bass line and harmony simultaneously. Stride is the foundation of jazz piano — Art Tatum, Fats Waller, Oscar Peterson all used it. Start slow (the jump is physically demanding) and build speed gradually.