A chord progression is a series of chords played one after another. Because we write chords as (see chords in a key), a progression works in every key: I–V–vi–IV is G D Em C in G major and C G Am F in C major.
Pick a key and listen. Each one is strummed on the guitar, one chord per to keep it short; in a real song each chord usually lasts a or more (the 12-bar blues gives each chord a whole bar).
The ii–V–I is usually played with seventh chords in jazz (ii7–V7–Imaj7), and the 12-bar blues uses the dominant seventh on every step (I7, IV7, V7). The dominant seventh is named after the V chord, the dominant, where it naturally occurs. These are four-note chords, which we look at next in seventh chords.
A phrase is a musical sentence. Its last two chords are called a cadence, and they decide how it feels: finished, softly settled or left hanging. Three endings everyone knows:
The strongest ending: the V chord pulls back to I. Countless songs end like this. Its proper name is the perfect (or authentic) cadence.
A softer ending. Hymns sing "A-men" to it, which gave it its nickname; its proper name is the plagal cadence.
The V chord promises home, but the music lands on vi instead, so it feels unfinished. This is the deceptive cadence.
To play a progression smoothly, choose close together, so your hand barely moves. Here are grips for one progression, picked that way, each chord shown once. Open grips come first where they fit; the shapes named after a letter (like "E shape") are the and CAGED shapes from Chords on the Guitar.
Build your own progressions in the progression tool.
Next: Seventh Chords