Although you can play a large number of chords in open position on the guitar, there are some chords which do not include open strings. In these situations, guitarists will often resort to playing "barre chords" (aka bar chords). When playing these barre chord, guitarists will use one finger to hold down multiple strings. Although you'll initially find barre chords to be difficult to play, they will provide you all the tools you need to play thousands of songs.
Barre Chords are "Movable Chords"
One of the key benefits of learning barre chords is the ease of moving them around the fretboard, in order to play different chords. When learning your basic open chords, there was a lot of memorization involved - a D minor chord had different fingering than an A minor chord, which had different fingering than an E minor chord. The good news is that you can use a single barre chord shape to play any minor chord - only the fret at which the chord is played needs to be adjusted. The bad news is, you will need to memorize the note names on the sixth and fifth strings to do this.
The following lesson will teach you to play four barre chord shapes - the major and minor shapes with root on the sixth and fifth strings. Because some of you may have already learned the minor chord with root on the fifth string, we'll start with that shape first.