#1
I really don't understand the Circle of Fifths. can anyone please explain it?? thanks!!
#2
Circle of 5ths

The Circle of 5ths (Co5) is generally used for determining what notes are in what key. Some people find it extremely useful, while others never use it. I think it's a very effective tool in constructing the diatonic major scales.

Now, there are 12 keys, one for each note in the western chromatic scale. In each key there are 7 different notes, A through G. What makes all these keys different, you ask? Well, in each key there are different variations of those 7 notes. Some have sharps (#) while some have flats (b). A sharp (#) indicates that the pitch is raised one semitone, while a flat (b) indicates lowering one semitone. When writing scales you must have one of each letter A through G. In other words, you cannot have A A# C C# E E# G A, or something like that! You must have A B C D E F G A. One of each letter.

Now, on to the actual circle! This is what it looks like:
.......C........
...G.......F....
.D...........Bb.
A.............Eb
.E...........Ab.
...B.......Db...
.....F#/Gb......


The top key is C. It is the simplest key, and has no sharps or flats. As you progress clockwise (flatwise) around the Co5, you add flats, 1 per key you progress. The same is true for sharps - as you progress counterclockwise, you add sharps, 1 per key. Therefore, using this rule, you can figure out how many flats/sharps each key has. Here's a quick list:
C - 0 sharps
G - 1 sharp
D - 2 sharps
A - 3 sharps
E - 4 sharps
B - 5 sharps
F# - 6 sharps
C# - 7 sharps (often written as Db, they are enharmonic)
~~~~~~~~~~~~~
C - 0 flats
F - 1 flat
Bb - 2 flats
Eb - 3 flats
Ab - 4 flats
Db - 5 flats
Gb - 6 flats
Cb - 7 flats (often written as B, they are enharmonic)

Now, how do you add these sharps and flats? There is a specific order to do it in! The order for sharps is F# C# G# D# A# E# B#, while the order for flats is roughly the opposite, Bb Eb Ab Db Gb Cb Fb.

Combining all of this knowledge, you can determine the notes of any key!
C - C D E F G A B C
F - F G A Bb C D E F
Bb - Bb C D Eb F G A Bb
Eb - Eb F G Ab Bb C D Eb
Ab - Ab Bb C Db Eb F G Ab
Db - Db Eb F Gb Ab Bb C Db
Gb - Gb Ab Bb Cb Db Eb F Gb
Cb - Cb Db Eb Fb Gb Ab Bb Cb
~~~~~~~~~~~~~
C - C D E F G A B C
G - G A B C D E F# G
D - D E F# G A B C# D
A - A B C# D E F# G# A
E - E F# G# A B C# D# E
B - B C# D# E F# G# A# B
F# - F# G# A# B C# D# E# F#
C# - C# D# E# F# G# A# B# C#

-SD