The Staff

Pitch is represented on the written page in terms of its vertical position on the staff.

The staff is a collection of five lines and four spaces, each of which represents a pitch-name.

If you consider all the pitches that are discernable to the human ear, from very low to very high, you will quickly realize that five lines and four spaces, in themselves, are insufficient to handle all notes possible.  Therefore, the staff must represent a specific range of pitches.  The range of the staff is determined by a clef.