The following points are generally true for major chords although there are a few idiosyncrasies to be noted.
When the fourth step is added to a major or minor triad, the chord is called suspended, or sus ( it has no 3rd so it is neither major or minor. A common chord movement is moving from a suspended chord to a major chord and vice versa. Play the Csus chord in the diagram and note how its fingered with the 4th finger playing the D string 3rd fret. Its sitting in front of the major 3rd (faded out note 2nd finger). Moving back and forth from Csus4 to C is a very common move in rock and pop music.