The ska stroke, or ska upstroke, is a guitarstrumming technique that is used mostly in the performance of ska, rocksteady, and reggae music. Ska strokes serve as a rhythmic base to a song, and may be doubled by the drums. This style of playing has a dance associated with it, the skank.
Ska strokes are considered a bouncing sound, going up then down in pitch. If a musician is using a general 1 and 2 and 3 and 4 and... on the downbeat, the sound is on the selected guitar chord, and then a ghost note is played on the string on the upbeat. The ghost note is achieved by lifting the fret hand off the fret a few millimeters. In reggae, ska strokes are played much slower than in ska.