How to Tell the Key of a Song

Every piece of music is written in one key or another, such as the key of Bb or the key of E or whatever. The key signature at the beginning of a score tells what sharps or flats are being used in the song, and therefore what scale the song is based on.

There is a key signature in all pieces of music.  It is signified just after the clef (the staff) and includes symbols for flats (b) and sharps (#).  When you take a careful look at the start of each of the lines in the music you will surely recognize a grouping of flats or sharps (never both at once).  They appear either on a space or on a line of the music staff and are put there to signify the notes that will be affected by them.  To say it a different way, if the #, or sharp, is placed on the top of a music staff, the F note will be played as F#.  This means that anytime the note F is played, no matter if it is in the staff’s first space, on top of the staff, or below or above the staff (this will be signified by the ledger lines) it will be played as F#.

When the note that has the flat or sharp signified in the key signature needs to be played as a neutral then an accidental will be put in front of the individual note.  In other words, if the music requires the playing of an F (neutral) in the G key, there must be an accidental put in front of it so that the person that is playing the music will not play it as an F#.

The key signature is put in place so that the sharps and flats will be limited on the actual notes in the piece of music.  Basically, by putting the # in the signature key it avoids the writer from having to put a sharp or flat by each note when the F is in the music.  It lets the musician know that each and every time the F note is required that it should be played as F#.  The lines of music will not be as cluttered this way and it will be much easier to be read.

Here are some common key signatures and the notes they affect:

Key of C: No flats or sharps
Key of G: One designated sharp (F#)
Key of D: Two designated sharps (C# and F#)
Key of A: Three designated sharps (C#, G# and F#)
Key of E: Four designated sharps (D#, F#, C# and G#)
Key of F: One designated flat (Bb)
Key of Bb: Two designated flats (Eb and Bb)
Key of Eb: Three designated flats (Ab, Bb, and Eb)

There is also a relative minor for each key.  The similarities of the relative minor and the major are nearly all the same (though started in a different place, the scales are the same) they are not thought of as the same.  The note that is found a minor third down from the major (key) is considered to be the relative minor.  It is also known as the sixth note in the major scale.  The A note is the six note of the C major scale, for example.  This means that the relative minor to the C scale is an A minor.  It is extremely common for music to use a particular key’s relative minor so if you know about them it makes understanding the chord progression in a song much easier to comprehend.

Here are some keys and their relative minors (keys).

A minor is the relative minor C
B minor is the relative minor for D
F# minor is the relative minor for A
G minor is the relative minor for Bb

When a musician is experienced and plays his music in a nontraditional setting, like when they play free style with not music to read, all he really needs to know is the key that the music was written in and he will be able to play the scales or melodies and the necessary chords that will allow them to play the song freestyle.

Last of all, it is very common for a song to change keys before the end of the song.  Musicians that are newer to the musical industry may find this very challenging.