Now, let's go with some examples.

I'm sure you know the song 'Knockin' On Heavens Door'. The whole song is basically written in 2 chord progressions;

So, we've got G – D – C – C and G – D – Am – Am progressions.

Before I say anything else I must let you know that this is usually not the way the chord progressions are being written. These should be written as I – V – IV – IV and I – V – ii – ii chord progressions. That would say to you much more, such as the key you're in, what should you do with melody on that chord progression, what modes are where, etc. But since I suspect you're not ready for that stuff yet, let's keep it on with letters, rather than roman numbers. That's why I named this lesson 'practical foundations', to make you work on practical side of chord progressions a bit more than on theoretical.

First thing you will probably notice on chord progressions is that they're often looped and one progression fits well after another. To achieve that, either you need to know music theory pretty well, or you need to have good aural skills. Sometimes both, and you should definitely work on both. You can always experiment which chord goes well after another, and create your own chord progressions in the way. Maybe even try singing over them. That will give you much better insight on how do they work under melody. And guess what, that's how you can begin working on your own songs!

Anyway, let's not go off the subject. We're on 'Knockin' On Heavens Door' chord progression. There's not much of a drama happening in the progression. It's pretty melodic and catchy, but it's not that musically agressive. But if you replaced C chord in the progression with B chord, for example, it would be much more dramatic.

If you reduced the lenght of each chord by double, you would get this pretty tough atmosphere. Kinda reminding of some punk songs. If you put some distortion on and omit the 3rds, you'll have a thing to headbang on whole night!

Another thing you can try is randomizing the chords you have in the progression. There's one very important thing you have to be aware of, or better said, you have to change your mindset to, is that you don't look the chord progression you got by randomizing chords as final product. Meaning, when you get x – z – y – x from z – y – x – x, and it doesn't work (one part of chord progression might sound off key or something), or it doesn't fit what you hear in your head, you have to analyze it and realize what makes it not to work. And then, change that part. Make it work. That's a great way of learning how do chords relate to each other. Here's one example of that;

If we changed the G – D – C – Am chord progression to G – D – Am – C, and it just doesn't fit the melody that's running in my head, but it's so close to it. 2nd chord is a bit too 'bright' or 'happy' when played under that melody, and I have to replace it with some other chord, and that new chord might not be among the chords of the progression we initially started with. With trial and error approach, or with experience, or with help of aural skills, or with help of music theory knowledge, I got to Em chord. So new chord progression would go: G – Em – Am – C. You can hear the difference now, right? Sometimes the difference will be more obvious, and sometimes not. It might be only a small detail that changes the whole picture.

Anyway, I strongly suggest you to create as much chord progressions as possible. Toy around with 'em and learn along the way. You will benefit a lot from that!