C or Do is the first note of the fixed-Do solfege.

In Western music, the expression "middle C" refers to the note "C" located exactly between the two staves of the grand staff, quoted as C4 in scientific pitch notation (also known as note-octave notation). It also tends to be in the middle of a keyboard, and it is near the top of the Bass vocal range and the bottom of the Soprano vocal range.

Although C4 is commonly known by the expression "middle C", the expression is somewhat keyboard-specific: players of some instruments may refer to the note by another name, and may use "middle C" to refer to a different note. For example, that note (C4) would be "low C" to the player of a Western concert flute (as it is in the lowest register of that instrument — see playing range), while C5 would be middle C. Nevertheless, the expression "middle C" is generally clear across instruments and clefs.

Within vocal music the term Soprano C, sometimes called High C, is the C two octaves above Middle C. It is named because it is considered the defining note of the soprano voice type. It is also called C6 in American note-octave notation. In European notation, it is c3. The term Tenor C is sometimes used in vocal music to refer to C5 as it is the highest required note in the standard Tenor repetoire. The term tenor C can also refer to an organ (musical instrument) builder's term for small C or C3, the note one octave below Middle C. In stoplists it usually means that a rank is not full compass, omitting the bottom octave.^[1]

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the middle C note is approximately 261.626 Hz. See pitch (music) for a discussion of historical variations in frequency.

For the frequency of each note on a standard piano, see piano key frequencies.

Designation by octave

Graphic presentation

Middle C in four clefs

Position of Middle C on an 88-key keyboard

Audio presentation

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