What is c flat?

C flat is a musical note that is one half step lower than C. It is represented by the same key on a piano or guitar, but is written with a flat symbol (♭) in front of the note. C flat is not commonly used in music as it is enharmonically equivalent to B natural, which is a more standard and commonly used note. However, it may be used in certain musical contexts where certain scales or chords require it.