the playing of certain chords while simultaneously increase the difficulty of playing other chords. Some tunings are used for particular songs and may be named after the song's title. There are hundreds of these tunings, although many are slight variations of other alternate tunings. Several alternative tunings are used regularly by communities of guitarists who share a common musical tradition, such as American folk or Celtic folk music. The various alternative tunings have been grouped into the following categories: dropped open both major and minor (cross note) modal instrumental (based on other stringed instruments) miscellaneous ("special"). Joni Mitchell is known for developing a shorthand descriptive method of noting guitar tuning where the first letter documents the note of the lowest string, and is followed by the relative fret (half-step) offsets required to obtain the pitch of the next (higher) string. This scheme highlights pitch relationships and simplifies the process of comparing different tuning schemes. String gauges String gauge refers to the thickness and diameter of a guitar string, which influences the overall sound and pitch of the guitar depending on the guitar string used. Some alternative tunings are difficult or even impossible to achieve with conventional guitars due to the sets of guitar strings, which have gauges optimized for standard tuning. With conventional sets of guitar strings, some higher tunings increase the string-tension until playing the guitar requires significantly more finger-strength and stamina, or even until a string snaps or the guitar is warped. However, with lower tunings, the sets of guitar strings may be loose and buzz. The tone of the guitar strings is also negatively affected by using unsuitable string gauges on the guitar. Generally, alternative tunings benefit from re-stringing of the guitar with string gauges purposefully chosen to optimize particular tunings by using lighter strings for higher-pitched notes (to lower the tension of the strings) and heavier strings for lower-pitched notes (to prevent string buzz and vibration). Dropped tunings A dropped tuning is one of the categories of alternative tunings and the process starts with standard tuning and typically lowers the pitch of ("drops") only a single string, almost always the lowest-pitched (E) string on the guitar. The drop D tuning is common in electric guitar and heavy metal music. The low E string is tuned down one whole step (to D) and the rest of the strings remain in standard tuning. This creates an "open power