General Information
Pitch, in music, is the relative highness or lowness of a tone.

Pitch is the musical term for the scientific concept of Frequency.
Frequency is the number of beats per second something vibrates to produce a tone.

The A below middle C is generally tuned to 440 beats per second.
The A above middle C would then be tuned to 880 beats per second.
Octaves, when in tune, function in a 1:2 or 2:1 ratio
When the frequency of a tone is doubled, the pitch will be one octave higher.
When the frequency of a tone is halved, the pitch will be one octave lower.

Pitches are named by using the first seven letters of the alphabet:
A  B  C  D  E  F  G

Relating pitch to the piano keyboard, the pitches on the left end are the lowest and the ones on the right end are the highest.

Using the pitch C as a reference point, the keyboard can be divided into octaves.
An octave is the distance between a C and the next closest C.

The C closest to the middle of the piano is generally referred to as
"middle C."  It is considered C4.

Starting with the lowest C they are numbered from left to right from C1 to C8.

All the pitches that lie between one C and the next are said to be in the same octave register.  The register includes the lower C but the upper C begins the next register.  See the diagram below.

C1  D1  E1  F1  G1  A1  B1  C2  D2  E2  F2  G2  A2  B2  C3  etc.
A Staff is used in music to allow us to precisely notate pitches.  It consists of 5 lines and four spaces, but may be extended through the use of ledger lines.

A Clef must appear at the beginning of each staff to indicate which pitches should be associated with the particular lines and spaces.

A Grand Staff is a combination of two staves joined by a brace.  The top clef will be the Treble Clef and the bottom will be the Bass Clef.