Examples of use
        The maj7 or Major 7th chord (sometimes written as △7 to avoid confusion with minor chords - eg. Gb△7) is usually found on either the I or the IV (1st of 4th) degrees of a major scale. 
        
So in Gb major, this would be Gbmaj7 or Bmaj7.
        
        
  
         
        In slightly more jazzy circumstances, you might play a maj7 chord on a more chromatic note of the score, as in this example, in Eb major: 
        
  
        Major 7th chords are one of the 
Diatonic 7th chords we talk about in the 
theory lesson here.