Also known as slide guitar. Most common in blues and rock music, bottleneck entails running a piece of smooth glass, metal or plastic up and down the neck of a guitar. When playing bottleneck, situating the slide directly on top of the fret, but not depressing the string to the fret, as opposed to pressing the string down behind the fret with normal playing, generates the tones. The term “bottleneck” refers to the early days of blues when players would use the necks of broken bottles to play slide guitar. To facilitate bottleneck playing, some players tune to open tunings.