In jazz improvisation, outside playing describes an approach where one plays over a scale, mode or chord that is harmonically distant from the given chord. There are several common techniques to playing outside, that include side-stepping or side-slipping, superimposition of Coltrane changes, and polytonality.
The term side-slipping or side-stepping has been used to describe several similar yet distinct methods of playing outside. In one version, one plays only the five "'wrong'" non-scale notes for the given chord and none of the seven scale or three to four chord tones, given that there are twelve notes in the equal tempered scale and heptatonic scales are generally used. Another technique described as sideslipping is the addition of distant ii-V relationships, such as a half-step above the original ii-V. This increases chromatic tension as it first moves away and then towards the tonic. Lastly, side-slipping can be described as playing in a scale a half-step above or below a given chord, before resolving, creating tension and release.