As children, some of us were taught these pitches but with different names, these being DOE, RAY, ME, FAR, SEW, LA, TEA.
In order to name all the pitches (or notes) discernible to the human ear the system of seven letters repeats itself.
The distance or "interval" between two notes of the same name, but a different pitch, is called an "octave". They have the same sound, but one is in a higher register than the other.
There are, in fact, twelve notes used in western music - so what of the other five? These are called "accidentals" and share the first seven letters, with an additional sign to indicate if they are higher (sharp ) than the note with the shared name, or lower (flat ).
The accidental's are the black keys on a keyboard, whereas the white notes are the "natural" notes of A, B, C, D, E, F, and G.
It is important to note that there are no accidentals between B and C or E and F.
Therefore the twelve notes are as follows:
C C# D D# E F F# G G# A A# B
NOTE: Csharp = Dflat , Fsharp = Gflat etc. although a traditionalist would tend to say B flat rather than A sharp.
Due to each accidental having two names they are known as "enharmonic" notes.
The distance or "interval" between each of the 12 notes is known as a SEMITONE (on a guitar, one fret = one semitone). Two semi-tones are equal to one TONE (one tone = two frets).
If you play all twelve notes in semitone intervals you are in fact playing the CHROMATIC SCALE.
A scale is any consecutive series of notes
that form a progression between
one note and it's octave.
The word scale comes from the Latin "scala", meaning ladder. This is a good way to view a scale - as a means of ascending or descending an octave, with each note representing a rung.
What differentiates one scale from another is not the notes that are used, rather it is the intervals between the notes. We can define a scale by these intervals - and what we end up with is a "STEP PATTERN".
Next --- How to work out scales