It is not always desirable to leave a chord ringing once it has been played. In electric guitar playing it is common to cut the sound of a chord off as soon as it has been played, making the rhythm very crisp.
The technique of cutting chords or notes shorter than their written value is called staccato. With chords containing open strings, staccato is usually achieved by placing the side of the right hand across all the strings immediately after strumming the chord. Staccato is indicated by placing a dot directly above or below the intended note or chord.