In literature, the volta, also referred to as the turn, is the shift or point of dramatic change. The term is most frequently used in discussion of sonnet form, in which the volta marks a shift in thought (often from question to answer or problem to solution). It is most frequently encountered at the end of the octave (first eight lines in Petrarchan or Spenserian sonnets), or the end of the twelfth line in Shakespearean sonnets.
The volta is significant because both the particular rhymes unifying the two quatrains of the octave and also the envelope scheme are abandoned simultaneously, regardless of whether this break is further reinforced syntactically by a full stop at the end of the octave (though it usually is), creating a decisive "turn in thought."
Voltas appear in various popularised sonnets.