There are so many combinations of tuning for guitars, I don't even think you can set a finite number because you can tune your guitar in any way and still find a name for that tuning that people can figure out. A half-step basically means that you change the standard tuning of each note a half step ( so a semi-tone) down (sometimes up). A half step is an interval and to the guitar it's a one-fret distance. So, E becomes Eb and so forth. (Eb Ab Db Gb Bb Eb) A full step is turning it to half steps down. basically all it is is changin notes, if you want me to explain more, like how to do it I will. But my carpal tunnel is hurting
