Slack-key guitar

Slack-key guitar (from Hawaiian kī hōʻalu, which means 'loosen the [tuning] key') is a fingerstyle genre of guitar music that originated in Hawaii. This style of guitar playing, which has been used for centuries, involves altering the standard tuning on a guitar from E-A-D-G-B-E, so that strumming across the open strings will then sound a harmonious chord, typically an open major. This requires altering (usually loosening) or "slacking" certain strings, which is the origin of the term "slack key". The style typically features an alternating-bass pattern, played by the thumb on the lower two or three strings of the guitar, while the melody is played by the fingers on the three or four highest strings.