Musical notation its "natural" form, which means that any sharps or flats applying to that note from the key signature or from accidentals are cancelled. Sometimes a courtesy accidental is used in music where it is not technically required, to remind the musician of what pitch the key signature requires. Following the key signature is the time signature. The time signature typically consists of two numbers, with one of the most common being "4/4". The top "4" indicates that there are four beats per measure (also called bar). The bottom "4" indicates that each of those beats are quarter notes. Measures divide
Key signature space in the key signature raises the notes on that line or space one semitone above the natural, and a flat lowers such notes one semitone. Further, a symbol in the key signature affects all the notes of one letter: for instance, a sharp on the top line of the treble staff applies to Fs not only on that line, but also to Fs in the bottom space of the staff, and to any other Fs. This convention was not universal until the late Baroque and early Classical period, however; music published in the 1720s and 1730s, for example, uses