Slide guitar is a technique used in playing the guitar where a smooth object, called a slide, is pressed against the strings. This allows the player to create a gliding sound, producing unique pitches and expressive tones. The slide can be made from various materials, such as glass or metal, and is often used in genres like blues, country, and rock. The technique can be played on both electric and acoustic guitars, and it often involves using open tunings to enhance the sound. Famous musicians known for their slide guitar skills include Duane Allman and Robert Johnson, who have influenced many guitarists with their distinctive styles.