In contrast to ordinary strumming, which is usually done either with a plectrum, or with several fingers as a unit, rasgueado generally uses only one digit (finger, thumb, etc.) for each strum; this means that multiple strums can be done more quickly than usual by using multiple digits in quick succession. Furthermore the outer (fingernail) side of the finger tips that is also used and, as a result, in that case, the strumming direction is reversed from the usual one, so it's a downstroke for the four fingers and an upstroke for the thumb.