[Music] using roman numerals in music is a widely used way of identifying chords and their sound qualities the system enables us to visually represent all of the different chords in a key it's also useful as they enable us to take a sequence of chords also known as a chord progression and then easily transfer that same progression into another key this can help when analyzing other songs it means you can work out a progression and then morph that same progression into any key that you'd like let's look at the scale of c major it uses just the white notes in between two c's [Music] let's then give each of these keys a number let's make a chord built on the first note letter c we'll call this chord one using the notes of the c major scale just the white notes they form a major chord in roman numerals this chord would be shown with an uppercase one if we go to the second note of the scale we come to letter d this is chord two and again just using the notes in the c major scale they form a minor chord because it's minor this chord 2 would be shown using lowercase if we keep going up the scale we next come to e starting on e and just using the white notes gives us an e minor chord chord three [Music] next we get f major chord four followed by g major chord five the next letter up letter a would give us a minor for chord six [Music] the seventh and final note in our scale before arriving back at c is the note of b if we form a chord starting on b using just the white notes then we get something a little different a diminished chord this is the odd one out compared to all the other chords it's neither a major or minor chord and sounds a little different diminished chords don't appear very frequently in music so don't worry too much about this one for now if we now look at all these chords in a major scale we can easily see which chords are major the uppercase and which chords are minor lowercase without diminished shown by the small circle on the end here so let's see how the roman numeral system can be used in practice still using the key of c major i'm going to use a standard chord progression of 1 4 6 and 5. that is the chords of c major f major a minor and then g major now instead of the key of c major let's change to the key of e major remember we need to use the notes of the e major scale in order to number the chords correctly the scale of e major has e f sharp g sharp a b c sharp and d sharp so taking the chord progression we had before let's play chord one this would be e major then chord four a major chord six c sharp minor and then chord v b major a chord progression cannot be copyrighted so it's okay to borrow a chord sequence from an existing piece or song and use it in your own music the roman numeral system will help you to work out the chord progression and then you can easily convert that into whichever key you would like