The category focuses on electric and acoustic guitar and bass guitar, but some of the information may be useful for other instruments such as mandolin and ukulele.  See also the 6-week course "Stanley Jordan Jazz Guitar 101 Workshop" which fits into multiple categories because it includes music theory and the art of learning.

(T-T1) Resources for 4thsTuning

4ths, or P4 tuning, has been around for quite some time, primarily used by 6-string bassists. More and more guitarists are discovering it, but there is precious little information available in the form of instructional materials, chord diagrams, etc. This course is intended to remedy that by pulling together info and links from various sources, some original, to make it easier for players to explore the world of P4.