Originally Posted by: dmitry.digi

Good quesrions and answers. I also was confused by capo role, thought it changes the keys and my thoughts of learnings keys recalculation when using capo prevented me to use it :)

Glad it helped. The capo doesn't change the key. It only makes playing in certain keys easier in certain situations.

For example if you want to play an E-flat major chord like this:

|--3-------|

|--4-------|

|--3-------|

|--5-------|

|--6-------|

|----------|

That's a handful. You can do it by barring at the 3rd fret & essentially turn a C major shape into a barre chord. Since the root note is on the 6th fret A string (an E-flat), you are using a C major shape to play an E-flat major chord. And if you do it this way, by barring you still have all the frets below the 3 fret available for the next chord, or anything else you might want to play along with this chord.

But you could also put a capo on the 3rd fret. This has the advantage of being able to just play a C major shape rooted at the 6th fret & play the same E-flat major chord voicing. You don't have to barre the entire chord shape! The disadvantage is you don't have access to notes below the 3rd fret as long as the capo is on the guitar. And that may be okay for the purpose of an entire song.

This is why capo users are frequently moving & removing their capo between songs.

Hope that helps!