In music, the sharps or flats placed on the staff to indicate the key for a composition or a section. Placement of the symbols on lines and spaces indicates which notes are to be altered by the sharps or flats; for example, a sharp on the top line of the treble clef governs every F on the staff and indicates the key of G major or E minor. Each set of major and minor keys is designated with a particular grouping of sharps or flats.

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