The 12-bar blues is one of the most popular chord progressions in popular music, including the blues. The blues progression has a distinctive form in chord structure and duration. It is, at its most basic, based on the I-IV-V chords of a key.
The 12 bar blues progression is the foundation of the blues. The whole blues genre is very minimalistic. Basically, all you need to get started is to learn the 12 bar blues progression and The Most Commonly Used Lead Pattern.
There are two common variations of the 12 bar blues progression. We’ll use Roman numerals to indicate each chord’s relationship to the key.
The “I” chord is the first chord in the key, “IV” is the fourth chord in the key, and “V” is the fifth chord in the key.
Or for now, you can just use the diagrams below to find them. They can appear on any fret up and down the fretboard to play in different keys.
OR:
These 3 chords are the most important chords in almost any genre, not just the blues. Usually without the heavy use of these 3 chords a song will lose it’s sense of key-which is bad news in almost any genre of music.
Many genre-including the blues-use these 3 chord on an exclusive basis. Ever heard someone poke fun at garage bands that only know 3 chords or 3 chord rock songs? Well, these 3 chords are the ones they are talking about.