A suspended chord replaces the third, the note that makes a chord major or minor, with the second or the fourth. Csus4 sounds C, F, and G, giving a slightly floating quality that is neither clearly bright nor dark.
The basic idea
The common forms are sus4, which uses the fourth, and sus2, which uses the second. In most cases moving to the original third creates a sense of resolution, but modern pop often keeps the suspended sound without resolving it.
Its role in writing and performing
Placed inside a progression, it adds a brief tension or a sense of width. It fits easily even where the melody avoids the third, and it is a simpler kind of color than a tension chord.
How to try it in a DAW
Move the E of a C chord to F to make Csus4, then move it back to E and compare. Sustaining sounds such as guitar, piano, or pads make the difference easy to hear.
How it differs from related terms
A suspended chord replaces the third, while a tension chord adds notes to a basic chord. Both are ways of changing the color of a chord.
When you want a sound that is not clearly major or minor, sus2 and sus4 are easy places to start.
