Each of the basic shapes also has variations which you create with the drop down menu next to the shapes creator. Here you can get familiar with the different sound of a 'major' or a 'minor' for example, as well as 'sevenths' etc. There's often more than just one way to make each of the chords presented, so further on you'll see that we've given you the ability to edit and record your own preferred versions.
Strings which show a small x at the nut, or head of the guitar neck, are muted. Muted strings are those you silence with nearby fingers while playing, so as not to hear them in the chord.