Consonant chords sound harmonious and pleasing, while dissonant chords elicit a feeling of tension and sounds like the notes are clashing.

In Western music the following intervals are considered consonant:

• minor third - For example from C to Eb
  
• major third - For example from C to E
  
• perfect fourth - For example from C to F
  
• perfect fifth - For example from C to G
  
• minor sixth - For example from C to Ab
  
• major sixth - For example from C to A
  

• octave - For example from C to C

On the other hand these intervals are considered dissonant:

• minor second - For example from C - Db
  
• major second - For example from C to D
  
• minor seventh - For example from C to Bb
  
• major seventh - For example from C to B
  
• tritone - For example from C to F#, tritone is also known as an augmented 4th or diminished fifth and it has an interval of 3 whole steps.

Most often dissonance is resolved by moving to a consonant chord. This makes the initial feeling of tension created by dissonant chords to reach a resolution. The common term for this is tension and release. However, dissonance doesn't always need to be resolved, also perceiving chords as dissonant tends to be subjective.