Linked from
The 27 pages that link to Musical notation, each with the reason it gives.
CounterpointRelated: Notation makes simultaneous melodic lines visible and writable.
MusicRelated: Notation preserves musical ideas in a form performers can interpret.
Sheet musicNarrower topic: Sheet music is a visible form of this broader system.
XylophoneRelated: Xylophone parts use pitched notation, typically on a treble-clef staff.