What makes a walking bass line?
A walking bass line generally consists of notes of equal duration and intensity (typically 1/4 notes) that create a feeling of forward motion. It is possible to add rhythmic variations, but in general, a walking bassline drives the song forward step by step.
What is walking style in jazz?
The goal of a walking bass-line is to outline the chord progression but with an interesting melodic line that provides a counter-melody (as above). In Jazz, bass-lines should generally not be too repetitive (unless you're intentionally playing a vamp – like in Blues or Boogie-woogie).