Sharp Key Signatures are always written in this order: F# C# G# D# A# E# B# The very next letter name above the last sharp is keynote of the major key. C major (with no sharps) must be memorized.
| Major Key | Relative Minor | Key Signatures |
| C Major | A Minor | No sharps or flats |
| G Major | E Minor | F# |
| D Major | B Minor | F#, C# |
| A Major | F# Minor | F#, C#, G# |
| E Major | C# Minor | F#, C#, G#, D# |
| B Major | G# Minor | F#, C#, G#, D#, A# |
Flat Key Signatures are always written in this order: Bb Eb Ab Db Gb Cb Fb The next to last flat is the keynote of the major key. F Major (one flat - Bb) and C Major (no flats) must be memorized.
| Major Key | Relative Minor | Key Signatures |
| F Major | D Minor | Bb |
| Bb Major | G Minor | Bb, Eb |
| Eb Major | C Minor | Bb, Eb, Ab |
| Ab Major | F Minor | Bb, Eb, Ab, Db |
| Db Major | Bb Minor | Bb, Eb, Ab, Db, Gb |
Circle of Fifths: Keys can be arranged in a circle in which each key is the interval of a fifth from the key before it and after it. Scales are built on each of these tones.
Enharmonic Keys: May be in sharps or flats.