Editing Major third (section)

== Consonance vs. dissonance ==
The major third is classed as an [[consonance and dissonance|imperfect consonance]] and is considered one of the most consonant intervals after the [[unison]], [[octave]], [[perfect fifth]], and [[perfect fourth]]. In the [[common practice period]], thirds were considered interesting and dynamic consonances along with their [[inversion (interval)|inverses]] the sixths, but in [[medieval music|medieval times]] they were considered dissonances unusable in a stable final sonority.

In equal temperament, a [[diminished fourth]] is [[enharmonic]]ally equivalent to a major third (that is, it spans the same number of semitones). For example, B–D{{sup|{{music|sharp}}}} is a major third; but if the same pitches are spelled as the notes B and E{{sup|{{music|flat}}}}, then the interval they represent is instead a [[diminished fourth]]. The difference in [[pitch (music)|pitch]] is erased in [[12 tone equal temperament]], where the distinction is only nominal, but the difference between a major third and a diminished fourth is significant in almost all other [[musical tuning]] systems. B–E{{sup|{{music|flat}}}} occurs in the C&nbsp;[[harmonic minor scale]].

The major third is used in [[guitar tunings]]. For the [[guitar tunings#Standard|standard tuning]], only the interval between the 3rd and 2nd&nbsp;strings (G to B, respectively) is a major&nbsp;third; each of the intervals between the other pairs of consecutive strings is a [[perfect fourth]]. In an [[guitar tunings#Alternative|alternative tuning]], the [[major-thirds tuning]], ''each'' of the intervals are major thirds.