Watch the String Snaps online guitar lesson by John Hatcher from Fingerstyle Blues Roots
Fingerstyle blues guitar is frequently played with no accompaniment. One picker and one guitar, that's it. Because of this, the guitarist has to keep the melodic content and the rhythmic content interesting. One cool and easy way to add a ton of rhythmic punch and dynamics to your fingerstyle blues is by using string snaps.
To snap a string, pick from under the string and pluck with a sharp but controlled outward movement. The resulting sound reminds me of the "crack" of a snare drum and it sounds great when you use this as a way to accentuate certain beats in the groove.