Have you ever thought to yourself, "Gee, why is it that every time I turn on the radio or listen to Spotify, everything sounds like a different version of the same song?" If you haven't, it might be worth a look into. Because although new songs are coming out all the time, gaining popularity and then being forgotten, most songs use the same structure as many other popular songs. If you don't understand the inner workings of music very well, that's fine. I'll try to keep it interesting.
To begin, meet the chord. The chord just happens when a collection of notes is played at the same time; the notes mix together to make the chord. And depending on what notes are mixed together, we get different kinds of chords, all living together in the music world. Unfortunately, these chords are stubborn, and they don't all work together all the time to make a song. But because musicians want to make music, they have to force the chords to work together, whether they like to or not. So musicians lay down the law by forcing all the chords into different keys.
A key is a specific group of chords that have certain musical elements in common, and it puts the chords in the order that we hear them in the song. The chords kind of liked this idea, and they wanted to make their group sound the best, so they started working together, which is why when we hear a song it sounds pretty good. The cool thing about keys is that we can change them, so that we can sing the same song either higher or lower.
Some of the keys had chords that were pretty happy, but some of the keys were full of chords that just were inconsolably sad and depressed all the time. We all know those people. The chords that were happy decided to call their groups major keys, while the sad chords went with the catchy name of minor keys. When a song's in a major key, it sounds upbeat, and when it's in a minor key, it sounds very sad. That's why Justin Beiber's "Love Yourself", which is in a major key, doesn't sound depressing, (just kind of arrogant) while "Boulevard of Broken Dreams" by Greenday, which is in a minor key, sounds quite down in the dumps.
There are certain chord progressions (or patterns) that seem to be more popular than others, and they run rampant in popular music. That's why "Blessed Be Your Name" can be sung to the tune of "Wagon Wheel": they both use the same tempo (that's a word that has to do with rhythm), and they use the same chords in the same order. Even more creative songs tend to share chord progressions: "Heathens" by Twenty-One Pilots uses the same chords as "Aaron Burr, Sir" from the musical Hamilton by Lin-Manuel Miranda.
Now, the chords didn't forget from whence they came: they were made out of notes. The notes are all arranged in octaves, which is a group of eight of these notes. So if you were to play a G on the piano you could go up and play A, B, C, D, E, and F before getting to the next G, and then it would start over. When the chords got used to working together in keys, they decided to number themselves like the notes in a scale.
So if "Blessed Be Your Name" were played in the key of G (which is a pretty low key for singing, but whatever), you'll get the chords G, D, Em (that little m stands for "minor"), and C, in that order, throughout the entire song. When put into numbers, G is one, or I (in Roman numerals); D is the fifth note from G, so it's a V chord; E is the sixth note from G, so Em is a xi chord (it's not capitalized because it's minor); and C is the fourth note, which is a IV chord. So altogether, you get a I-V-xi-IV chord progression, which is extremely common in popular music.
Songs that share the I-V-xi-IV progression are numerous, and they include pieces like "Don't Stop Believing" by Journey, "Can You Feel the Love Tonight" from The Lion King, and even part of "Let It Go" from Frozen. In Christian contemporary music, this would extend to "Today Is the Day You Have Made", "Let Everything that has Breath Praise the Lord", "Here I Am to Worship", "We Believe", and "Your Grace is Enough", to name only a few.
There are other common chord progressions, but this is the most common of them all. Try it sometime: when hearing one of these songs on the radio, try singing a different song that uses the same chords. It's tons of fun, and it annoys everyone around you who are just trying to listen to their favorite pop song. Happy humming!
