The key signature is the sharps or flats, or absence of either, at the beginning of a piece of music, indicating the sharps, flats and naturals belonging to the key of the music. Since a major or minor scale, the two now in common use, has a fixed order of tones and semitones (whole steps and half steps), these can only be preserved when there is a change of key note by the addition of sharps or flats. In the major scale, for example, there are semitones or half steps between the third and fourth degrees and seventh and eighth degrees of the scale. In the scale of C major, played on the white notes of the piano, these semitones fall between E and F and between B and C, a fact apparent from the piano keyboard, where there is no black key between the notes that form these pairs. To keep the same pattern in the scale of G, the note F must be raised to F sharp, so that there is still a semitone between the seventh and eighth notes of the scale. Major key signatures can be calculated on the same system. Each key with an extra sharp starts on a key note a fifth higher, while the keys with flats are in a descending order of fifths. C major itself has no sharps or flats, G has one sharp, D two, A three, E four, B five, F sharp six and C sharp major seven, each new sharp the seventh note of the scale. Descending in fifths, F has one flat, B flat two flats, E flat, three, A flat four, D flat five, G flat six and C flat seven, each new flat the fourth note of the scale.