Well the scales in western music are broadly classified into majors and minors….first let me explain to you what are majors….Majors are the scales that almost I believe coincide with the classical sa,re,ga,ma…there are totally 12 notes in music….they are
A,A#,B,C,C#,D,D#,E,F,F#,G,G#…….notice that the notes B and E don’t have any #’s(pronounced as sharps)…… the difference in the frequencies of two adjacent notes is known as a semitone and the difference between two notes with a note between them is called a tone…..well for example the difference between the A note and B note is called a tone and the difference between A and A# is called a semitone…even the difference between the notes A# and B is a semitone…..but again notice that the difference between the notes E and F and the notes B and C is only one semitone and not one tone as it is normally confused to be……so now there are scales(referring to majors and not minors) possible starting from each of the above notes…..
Consider the C major scale which has the following notes and is taken as the basis for all other notes…..
C D E F G A B C…..notice that it has no sharps….so a C major scale is considered to be the base…..now analyzing the C major scale we get the pattern of the difference between two consecutive notes in the scale as
T T st T T T st…where T stands for a tone and sT for a semitone….. this means that the difference between the first and the second note is a tone in the scale and the difference between the third and the fourth note is a semitone……therefore comparing it with the classical notes of sa re ga ma…we get the difference between sa and re to be a tone and ni and the higher sa and the difference between the ga and ma to be a semitone.So now one can write any scale…..say if u want to write the G major scale u get
G + tone = A
A + tone = B
B + semitone = C
C + tone = D
D + tone = E
E + tone = F#
F# + semitone = G
So the scale goes like G A B C D E F# G……
and all other scales are just a fret away!!