The circle of fifths (CoF here-in) is an imaginary circle (Imaginary in the sense that you have to arrange it on paper to get the circle) that is used to find the 5th of each key, and then the sharps associated with it. Ascending, going from C Major (0 sharps, 0 flats) is G, D, A, E, B, F. I remember it as Cows Graze Daily At East Brunswick Forever. East Brunswick is the town where I live, so it may be more practical to change the E and B acronyms to something else.
Quote by mjkshreds
thanks for the advise, how can the circle of 5ths help me thow.

It can help you determine the sharps and flats of the key.
The circle of fifths basically shows you the most common interval in music. The fifth (clockwise) and fourth (counter-clockwise.)
I would say it is completely necessary to have a grasp on it. Being that in hard rock and metal, basically every rhythm guitar part ever is straight fifth chords.
Wikipedia has a great article on it.
if you know what notes are then..
its basically a chart that tells you what sharps/ flats are in each scale.. and it can tell you what minor keys are relative to major keys,

for example, C major is relative to A Minor(to get the relative minor scale.. you use the same notes in a major scale but you start on its 6th note. 'A' is the 6th note in the 'C' major scale)... and you will find neither scale has sharps/flats in them..

now, if you start a major scale on C major scale's FIFTH note, which is G. you will find the G major scale has 1 sharp.. and you will find its relative minor which is E minor.

if you repeat this pattern with G major.. youll get its fifth which is D.. and you will know that the D major scale has two sharps..

and it repeats this pattern going backwards with flats.. and it stops until the scales basically become the same.
and it can help you because it relates to chords and scales.. something you should know