In music a walking bass is a bass accompaniment generally consisting of unsyncopated notes of equal value, usually quarter notes (known in jazz as a "four feel"). Walking bass lines are used in rock, blues, rock-a-billy, r&b, gospel, latin, country, and many other genres.
Many boogie-woogie basslines are walking bass lines:
In this case "walking" appears to refer both to the steady duple rhythm and to the strong directional motion created, from C to F and back in the first, and from root to seventh and back in the second.(Courtesy of Wikipedia)
Walking Bass refers to a style of guitar playing where chords and a moving bass line are played at the same time. Each beat of each measure receives a separarte bass tone creating a sequence of quarter notes in the bass. There was a great article in the February 1990 issue of Guitar Player entitled "Joe Pass' Guide to Walking Bass Lines and Beyond."
To get you started, below is an example of a walking bass line added to a typical "I-VI-II-V" Ragtime Progression. This progression can be played using all Shell Chords as follows: |C7 Bb7 A7 Eb7|D7 Ab7 G7 C#7|.