Flat (music)

In music, flat, or Bemolle, means "lower in pitch." In music notation, flat means "lower in pitch by a semitone (half step)," and has the symbol (). The Unicode character " (U+266D) is the flat sign. Its HTML entity is &amp;#9837;.
Under twelve tone equal temperament, "C flat" is the same as, or enharmonically equivalent to, "B natural", and "G flat" is the same as "F sharp".
Double flats also exist, which look like and lower a note by two semitones, or a whole step. Sometimes you will encounter half or three-quarter flats. The Unicode character '𝄫' 𝄫 (U+1D12B) represents the double flat sign.
A triple flat can be found, but it is very rare. It lowers a note three semitones. 
The note "A flat" is shown in musical notation in Figure 1, together with "A double flat". 
In tuning, flat can also mean "slightly lower in pitch". If the same note is played on two instruments at the same time, the lower-pitched one is flat compared to the higher-pitched one.
A half flat, showing quarter tones, is sometimes shown with a flat with a slash () or a reversed flat sign. A three-quarter flat is represented by a half flat and a regular flat.