Open-position chords are immobile because they utilize open-string notes, which can’t be moved up and down the fretboard like fretted notes can. In order to create a moveable open-position chord shape, we turn to barre chords.

By laying your first finger across the fretboard like a "bar", your finger acts as a capo, covering any strings that would otherwise play open-string notes. Barre chord shapes are based on open shapes like E and A but add the barre to compensate for the open strings. With a barre shape, you can move the chord up and down the guitar neck.

Link to Beginner guitar Vol 2.