The Basics of Music Theory - Part 3 (Key Signatures)
In our last installment (The Basics of Music Theory - Part 2 (Intervals & the Major Scale)) we covered the major scale. With the scale comes the identifying of keys. That brings us to today's subject, key signatures.
Defining A Key Signature
The key signature is found at the beginning of every line of music in a given piece of music notation. I mention the words "music notation" because I know some guitarists read tablature and key signatures do not exist in tablature. It is the sharps or flats that come from the major scale that defines the piece of music you are playing. Therefore, it is just a device to indicate what specific key you are playing in for that particular piece.
All music could be written without a key signature but then all the accidentals of a key would need to be written every time they were needed in the music. This would make reading notation very cumbersome. Hence, a key signature which has the notes of E major (a favorite guitar key) would indicate that the entire piece is in E major. It also indicates that when you see that particular note, at any place on the staff, it would need to be played according to the key signature (i.e. if the key signature says F-sharp, then you need to play all notes appearing to be F as F-sharp).
The key signature of E major generally confines the piece to using the notes in the key of E major. Obviously this would restrict composers from true expression. Therefore, other notes can be added using accidentals (sharps or flats not found in the key signature).
Key Signature Relatives
Each key signature can indicate two actual keys. The first is the major and the second is the minor. The minor key "related" to the major is called the relative minor and vice versa (relative major). The relative minor of a major begins on the sixth degree of the major scale. Let's take the key of C major. The notes in C major are C, D, E, F, G, A, B, and C (scale degree: 1, 2, 3, 4, 5, 6, and 7). The notes of the relative minor, A minor, begin on the sixth degree. This makes the notes of A minor A, B, C, D, E, F, and G.
Chart Of Major And Minor Key Signatures
The key of C major mentioned above has no sharps or flats. All the notes in that key are considered "natural." Therefore, the key of C major (or A minor) have been left out of the chart below giving all the sharp and flat major and minor key signatures.
If you missed our last part in this series, then check out The Basics of Music Theory - Part 2 (Intervals & the Major Scale). If you're good with this, then proceed to The Basics of Music Theory - Part 4 (Cycle of 4ths). If you would like to have an useful iOS app for music theory and ear training, then might I suggest Tenuto. It is an awesome app to push your musicianship to new levels. I know it has mine!