Sweep picking

Sweep picking is a technique used on the guitar in which multiple, adjacent strings are articulated, and thus sounded in succession without ringing together, with a single pickstroke much akin to the strumming of a chord. Almost exculsively applied for arpeggios, the movable shapes of which lend themselves to it, Sweep picked licks (lead phrases) were popularized by Yngwie Malmsteen, Tony MacApline, Vinnie Moore, Michael Angelo Batio, Jason Becker and Marty Friedman, and other shredders. Although few strokes are requisite in a sweeped arpeggio, almost all of them need a minimum of two strokes, if a chord tone is utilized without legato facilitating the fluidity; six-string sweeps such as the minor shape need 6 strokes sounding 15 notes, to pass through two octaves and return, this assumes that the chord tones are implemented symmetrically on both the 6th and 1st strings. The grandise five string C sweep that summerizes Yngwie's "Far Beyond the Sun" (the epitome of the shredding genre, and quite melodic in my opinion) makes necessary 8 articulations to sound 13 notes. 

The three string (minor) sweeps are usually either the top three of a 5 string sweep, where the notes are (in descending order) for example B-G-E-B 2, 1 1/2, 2 1/2 steps between them, thus the 12 half steps of an octave, or the open A Minor shape 2 1/2, 2, 1 1/2, also one octave; the aforementioned sweep that virtually concluded Yngwie's opus, was a combination of 2 stacked open minor shapes C-G-D#-C-G-D#-C. (B)-G-E-B-G-E is a five string sweep, the b in () is the "Chord tone ornamentation" A six-string minor shape is a this, A-(C)-E-A-C-E-A-(C). Chord tone ornamentation is a continuation of the chord that requires an articulation change by way of two notes on a single string, and another change to begin on the other notes in the sweep, if any, or on the return to the origin. 

While the ornamentation of arpeggios may be accomplished through a change in pick articulation, upstroke or downstroke, legato techniques, hammer-on, pull-off, or, more rarely (in my experience), slide. The chord may be further continued to the next note via means of tapping, as used by Michael Angelo Batio, or may be employed to sound notes in a scale wherein the chord lies, but they notes do not necessarily lie within the chord, T= tapped     T
                                                                  i.e. A-C-E-A-C-E-D-C-B-A-E-C-A. Note that while their  
                                                                      Ascending   Descending
Note that while the duration is extended, some of the fluidity that an arpeggio is naturally endowed with is lost due to these passing tones which change the intervallic leaps in the embellished arpeggio.

Economy picking refers to the sounding of two adjacent strings, that do not (usually) ring together, in succession, with the use of a single pickstroke, which is occassionally employed by Shredders to change strings while in the throes of an alternate picked lead. 

To prevent the notes of either of these techniques, lift your finger off the string as soon as the note is sounded, but prior to the striking of the second note; if two or more adjacent strings have the same fret, instead using a rolling motion that relieves pressure on the first string, retaining enough to mute it, while appling it to the next.