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.