Much guitar music comes with capo information designed to make the playing of the song easier. The chords in the original key are much harder to play than in the transposed key.
When more than one guitarist wants to play such songs together, normally all have to use capos to play together in the new key. When someone does not have a capo or when they all want to play in the new key without using a capo, those who want to play the melody or other parts usually have a very difficult time transposing the notes to the new key.
An alternate approach that solves this problem is for guitarists to learn how to transpose mentally the notes so that they can be played in the new key without the use of a capo. My Capo 1 Note Transposition Chart shows how to do so for songs that are marked as “Capo 1”!
Using this chart and practicing such transposing opens up a vast number of additional possibilities of playing guitar songs in various keys.