Barre chords are a type of guitar chord where one or more fingers are used to press down multiple strings across the guitar fingerboard (like a bar pressing down the strings). Barring the strings enables the guitarist to play a chord not restricted by the tones of the guitar's open strings. Barre chords are often referred to as "movable" chords, as they can be moved up and down the neck as needed. They are commonly used in most popular and classical music and are frequently used in combination with "open" or standard guitar chords. Frequently referred to as "jazz" chords, they are typically used for more complex chord voicings and playing in keys not suitable for the more basic open chords of the first position of a standard-tuned guitar.
Fretting a barre chord is the same as retuning the guitar a number of half-steps higher, playing the original open chord, and then tuning the guitar back down. Its primary purpose is to shift any of the open string chords an arbitrary number of half steps down the neck of the guitar. For example, playing the E major chord with a bar across the fifth fret is equivalent to playing an A major chord, five half steps higher than E.
Tonality is affected by a barre chord. Because the strings are no longer open, they do not resonate as brightly or long as an open chord. The sound is arbitrarily muted by the pressure placed on the bar--heavy pressure in the center of the frets produces less muting. Therefore, when playing barre chords, it is important to practice maintaining adequate pressure, as the technique is tiring for beginners.
(Courtesy of Wikipedia)
Barre Chords are movable chord shapes, with no open string notes, that can be played in any position on the fretboard. They are characterized by the use of the index finger to press down more than one string at a time like a capo. Barre Chords, like all movable chord shapes, get their chord name from their Root note. Barre Chords are more easily played on electric guitars and most frequently encountered in Rock Music.The fingerings for the two most common Barre Chords are presented below.