For more information from the source site of this video please visit: http://secretguitarteacher.com/youtube/advanced/theory/lcE20kBpzn0/83837700-understanding-key-signatures-1.php In this lesson we are going to tackle a major level on the Pyramid of Guitar Music Theory and gain a deeper understanding of Key signatures. The outcome of working through this lesson will be an ability to know what key a piece of music is in just by glancing at it. Also, some insight into how different keys relate to one another, and how to calculate how many sharps are in a particular key. If we check the arrangement of notes in our C scale we can work out that there is a Tone between C and D... a Tone between D and E, bit only a semitone between E and F.. Remember these are two notes on the keyboard that don't have a black note separating them So, without any alteration the notes CDEFGABC already conform to the Major Scale Formula. There is therefore no need to add any sharps or flats to the key signature in this key. Next we count up the scale of C Major to step 5. We do this because this lesson is called the Circle of Fifths. This gives us the note G. So the G scale is the next one we are going to look at: Again we start by laying out the letters from G to G. Then we analyse the gaps between the note. But this time you'll notice that in order to make the scale fit the formula we have to sharpen the seventh note from F natural to F#. The way this is expressed in standard notation is to place one sharp sign at the start of the music on the top line of the stave. It is placed on this line because this is the line where the note F is normally positioned. This instruction tells you to play every F note you encounter as an F#. So here is the essence of what this lesson is all about -- that key signatures have the purpose of keeping notes in the key the correct distance apart from each other. And in the case of the Major Keys the correct distances are given by the Major Scale Formula of TTSTTTS.