A capo allows us to simplify tricky chord fingerings that often happen in "difficult" keys like A♭, B♭ or E♭.
But there is more to the simple Capo than that!
The capo isn;t limited to simply fixing technial fingering problems-it also has the potential to generate very cool effects - especially in "guitar friendly" keys, the capo can really open up a world to you to allow your guitar to shine, especially if playing with another player!
For example, take a look at the lick below. It's a basic progression from A to D to E, it's easy enough to play in "open" position. But imagine you are playing with another guitarist and you don't want to play the exact same chords/voicing that they will be using. Or perhaps you have a bunch of songs in your set with the same set of chord changes...it would be nice to break them up a bit.
In either situation you'll want some variety! Using a capo makes it really easy, and it allows you to find fresh, new, exciting patterns through familiar changes.
As you play though this notice all the spicy sounds that sometimes emerge because of the adjacent strings ringing together.
In bar 1, D and E for a chimey major second as you ascend and descend the A and D arpeggios.
This controlled dissonance gets even more cool in bar 2 when you create a minor second by playing G♯ and A on adjacent strings.
Thanks to the capo the fingerings are simple, yet the harmony is actually kind of "complex" or "mature" sounding.
As always the guitar pro file, and printable pdf is in the dropbox for Fretboard Infinity Loop customers. (not sure what that is? Email me)
If you're not sure what I'm talking about when I say things like minor or major second - perhaps do yourself a favour and grab a pdf copy of my book "Basic Music Theory for Guitarists"! (also available in full-colour print version from Amazon)