An inverted chord is a chord which has a note other than its root note as the bass note. To invert a chord you move the lowest pitched note to the highest pitched position.
When the root note in a chord is the lowest pitched note, then the chord is said to be in the root position, or in its normal form. Otherwise the chord is inverted.
A triad of a D Major chord, is made up of the following notes; D, F#, and A. D is the root note of the chord,
When D is the lowest pitched note, the chord is in root position: D-F#-A.
When F# is the lowest note, the chord is said to be in its first inversion. F#-A-D,
When A has the lowest pitch, the chord is said to be in its second inversion. A-D-F#,