Drop B tuning is a heavy metal guitar tuning for a six-string guitar where the strings are tuned to B-F#-B-E-G#-C# (or B-G♭-B-E-A♭-D♭). This is a "drop 1" tuning in the key of C# (i.e. tune the whole guitar down a minor third from standard tuning, then the 6th string is lowered an additional whole step down). As a result, it uses the same fingering as all other "drop" tunings.
Heavy metal guitarists rarely use Drop B tuning when tuning their guitars.  