A pick slide (or pick scrape) is a guitar technique most frequently used in the rock, punk and metal music genres. The technique is performed by holding the edge of the pick against any of the three or four wound strings and moving the pick along the string. As the pick moves across the string, the edge of the pick scratches the string's windings in fast succession causing the string to vibrate and produce a note. This quick rattling of the pick's edge against the windings also gives the resulting note a scraping or harsh sound.
The pitch of the sound rises as the pick moves to the bridge and lowers as the pick moves away from it. Since pick slides usually start near the bridge and end over the higher frets, these slides have a tendency of gradually lowering the pitch. This technique is most efficient for the electric guitar with high gain. It isn't loud enough to be distinguishable from the ordinary fret noise on an acoustic guitar or an electric guitar without distortion. Pick scraping may cause wound strings to decay at a slightly quicker rate due to the essence of the technique. Thinner picks made of more strong materials tend to perform better in this respect.
The first use of the pick slide is attributed to Bo Diddley and can be heard in the opening of his song "Road Runner."
Example of pick slide
Video lesson for pick slide
Red Jumpsuit Apparatus - "Face Down" official music video. Example of pick slide is on 0:27.