Every song has a key signature.
A key signature tells us what originating tone a song is to be performed in. It can either be major or minor.
There are 12 tones in music of equal value. Imagine tones as blocks:
The distance between each tone is called a half-step interval.
Since there are 12 tones in music, there are 12 Key Signatures in music. 7 of these are primary key signatures called A, B, C, D, E, F, and G.
The remaining 5 key signatures are secondary key signatures. They have dual names, meaning they can be called sharp or flat. A sharp means half a step higher and a flat mean half a step lower. Sharps are represented by a “#” and flats are represented by a “b”. The 5 secondary key signatures are called G# or Ab, A# or Bb, C# or Db, D# or Eb, and F# or Gb.
The 12 Key Signatures: