Topic summary
Pattern Picking

Extracted from the Wikipedia article Fingerstyle guitar.
Country blues
Fingerpicking (also called thumb picking, alternating bass, or pattern picking) is both a playing style and a genre of music. It falls under the "fingerstyle" heading because it is plucked by the fingers, but it is generally used to play a specific type of folk, country-jazz and/or blues music. In this technique, the thumb maintains a steady rhythm, usually playing "ostinato bass" or "alternating bass" patterns on the lower three strings, while the index, or index and middle fingers pick out melody and fill-in notes on the high strings. The style originated in the late 19th and early 20th centuries, as southern blues guitarists tried to imitate the popular ragtimepiano music of the day, with the guitarist's thumb functioning as the pianist's left hand, and the other fingers functioning as the right hand. The first recorded examples were by players such as Blind Blake, Big Bill Broonzy, Skip James, Blind Willie McTell, Memphis Minnie and Mississippi John Hurt. Some early blues players such as Blind Willie Johnson and Tampa Red added slide guitar techniques.