When singing a song like "Happy Birthday," no one asks for a key before singing because we can sing melodies "relatively." That is, we have a very basic singing understanding of intervallic (distance between notes) relationships because of many years of talking, singing, humming, listening to music, etc.
We can apply this same concept to our understanding of the guitar. How would you like to play chords to songs with the same ease as singing "Happy Birthday"? It's very possible if you understand this concept and start applying the tools as I'll reveal in this course.