What Are Alternate Tunings?
Alternate Tunings means different things to different people. Some mean the way the strings of a guitar are tuned, while others mean the way the frets are placed.
In a guitar-o-centric world, alternate tuning means different ways to tune the strings of a guitar. If you're wondering why someone might want to do this, click here. Several years ago I catalogued a large number of such tunings, and have recently translated it into (reasonably) web friendly form. I call it the Alternate Tuning Guide. Recently, I translated this into an interactive version, which uses the (free) Wolfram .cdf player.
Others mean alternate in a much more drastic sense, where the pitches of the notes differ from the standard 12-tone equal tempered tuning (the tuning used by the piano and most Western popular and orchestral instruments), which divides the octave into 12 equal parts. Why not divide the octave into 10 equal parts? Or 19 equal parts? The resulting intervals are often called microtones and the resulting music is microtonal, but this is only a description of the tuning, and is not a description of musical style. Several web sites are devoted to the exploration of microtonality, including the Microtonal Synthesis Page and John Starrett's Microtonal Homepage.
For many reasons, 19 tone equal temperament is a popular alternative tuning. In 1991, I wrote an article that appeared in Experimental Musical Instruments that describes playing a 19 tone guitar, and includes 19-tone fretboard designs and chord charts. This is now available on line here.
...or come to my home page for more information.