Drop D tuning
Guitar tuning in which the lowest string is lowered a whole step (D instead of E).
What it means
In drop D tuning, starting from standard tuning E-A-D-G-B-e, only the lowest string is lowered a whole step from E to D, while the other five strings remain unchanged. This allows a low fifth or octave to be fretted against the neighbouring strings using a single finger on the lowest string.
Musical use
Drop D tuning allows, especially in rock and metal music, deep, powerful power chords that can be fretted with a single finger across several frets without the hand needing to change position. It is also valued in folk and fingerstyle guitar music, where the low D bass note opens up additional harmonic possibilities for pieces in D major or D minor.
Drop D tuning should be distinguished from fully alternative tunings such as open D tuning, where several or all strings are changed to produce an open D major chord on the unfretted strings. It differs in that only a single string is retuned, and the familiar fingering patterns of standard tuning remain largely intact.
Performance practice
Lower the lowest string carefully, checking it regularly against the octave on the D string to hit the exact pitch, since tuning it down too far noticeably changes the string tension. When switching between standard and drop D tuning during a piece, do so as quickly as possible, for instance using a tuning peg or a drop tuner, to avoid breaks in the flow of playing.