When a song consists of notes from a particular scale, it is said to be written in the key which has the same notes as that scale. Therefore songs that use notes from the G major scale are said to be in the key of G major.
Songs in the key of G will contain F sharp (F#) notes. Instead of writing a sharp sign before every F note on the staff, it is easier to write just one sharp sign after each clef. This means that all the F notes on the staff are played as F#, even though there is no sharp sign written before them. This is called a key signature. The following example is in the key of G major and uses a key signature. Note that the Tab notation does not use a key signature.
Rhythm Pattern