I,IV,V what??

They refer to chords within a scale. If you start with the root, the scale positions are 1, 2, 3, 4, 5, 6, 7, then back to 1 again. It is an abstraction of the scale, so it doesn't matter which scale I'm talking about, I know that 1 is the root, 2 is the second degree (position), etc.
A basic chord triad is made up of the 1, 3 and 5 degrees of a scale:
C major: C, D, E, F, G, A, B
D major: D, E, F#, G, A, B, C

Chords are also abstracted, but to differentiate them from scale degrees, they are shown as roman numerals. So, I, IV, V show a chord progression, which uses the chord from position 1 (the root), 4th position and 5th position. So, this progression, in C, would be C (I), F (IV), G(V) and, in D, D (I), G (IV) and A (V). Upper case numerals (I, IV, V) are for major chords, while lower case (ii, iii, vi, vii) are for minor chords.

To expand on what Greybeard said, here are the I (Root) IV (4th) and V (5th) chords for the most commonly used keys for guitar.


Key I IV V

B B E F#


How are they used? Many chords are used in various songs, but many thousands of songs are built on just the I, IV, and V chords only. This is especially true with Blues, but many Rock, Country and even other styles like Jazz have many songs using just 3 chords.

A very common progression is the 12 bar blues. Thousands of Blues songs have been written with this progression.


I/I/I/I/IV/IV/I/I/V/IV/I/V

A/A/A/A/D/D/A/A/E/D/A/E


Each slash above is a measure, usually 4 beats long. So strum 4 beats for each measure shown above. You will probably recognize this famous progression as soon as you hear it.

There are many other famous progressions shown with Roman numerals. Take the I, VI, IV, V progression. This is the famous chord progression heard in thousands of songs from the 50's.

In the Key of C

C, Am, F, G

In G this progression would be

G, Em, C, D

Strum 4 beats (one measure) for each chord shown above. You will probably recognize this famous progression as well.

So the Roman numerals are just used to show what chords are used. This is how progressions are shown. And progressions are just a very common (but not always) series or order of chords played.

Wes, great explanation on the progression. I just wanted to add a comment on why the VI chord is a minor chord.

Edit: this has had the minor side effect of me taking the time to make sure I know what I'm talking about. I defintely needed to work this out once more to be sure I fully understood it.

Take the key of C. (C D E F G A B C) The C major chord contains the 1, 3 and 5 notes from the scale, in this case C-E-G.

The IV chord of C is the F. The F major scale contains F G A Bb C D E F. Take the 1, 3 and 5 from there and you get the F major chord of F A C. Those three notes still lie in the C major scale, no problems there.

The V chord of C is the G. (G A B C D E F# G) Same principle applies to get the G chord of G B D. Again, those notes are still contian in our key of C, so we are good to go.

Now, let's look at the VI chord in the key of C, the A. The A scale is A B C# D E F# G# A. That means the A major chord is A C# E. Wait a minute, that C# sure isn't in the C scale. So, to stay purely in the notes contained in our key of C scale, let's flat that C# to a C and play A-C-E. That chord is the A minor chord.

So, after all that, you've gotten a LOT more than you set out asking. Hope it helps in some small way.

Ok, well those are some great explanations and i hope i can understand them once i read it over again and over, and over...

This is one of those occasions when we point you in the direction of the lessons on this site. what's the best place to start? Anything by David Hodge - that's the name of our superhuman brain-replicating computer we plug in every once in a while when we need a bunch of top class lessons.

Best,

A :-)