B Suspended 4th
sus4
0 - 5 - 7Root + perfect 4th + perfect 5th
About B Suspended 4th
Bsus4 replaces the D♯ of a B major chord with an E — B, E, F♯ — and on guitar it inherits all the difficulty of its parent. There is no open-string version; the chord is a barre at the second or seventh fret, and its usual job is to delay a resolution that is already hard to reach.
The notes
B, E, F♯. No third, and the fourth leans toward the D♯ it replaced. In the key of E that leaning is doubly useful, because the chord also points toward the tonic of the key.
The same three notes read from E give Esus2, which does not lean at all. Whether the chord is a delay or a colour depends entirely on which note the bass takes.
On the fretboard
Second fret with the root on the A string, or seventh with the root on the low E. The seventh-fret position is more comfortable and more common.
A partial voicing on the top four strings drops the barre and is what most players use in fast passages, letting the bass supply the root.
Where it shows up
In the key of E as a suspended dominant — B7sus4 is the more common form, and the plain triad version appears mainly in rock where the seventh would be too jazzy.
It also appears in the key of B itself before the tonic, though that key is rare on guitar and usually arrives through transposition.
The suspension is also common in worship and stadium rock, where the guitar sustains it while the band arrives — the chord is loud, unresolved and easy to hold, which is exactly what those arrangements need.