Here are some other Key Signatures. Try relating them to the Major scales in the Scales section.

To summarise, every song you play is in a key. The key is the centre of the chords and tunes contained within a song. When people say things like "Lyin’ Eyes is in the key of C", you would know that the chords and melody of Lyin’ Eyes are based around the C major scale and the chords that occur in the key of C.

The idea of a key having its own set of chords is something that is very important to understand. It helps when you are figuring out songs or start writing your own songs and solos. This is covered in the Chords in Major Keys section.