Syd Barrett was the driving and creative force behind Pink Floyd. Of course, he only was heavily involved with their first album, The Piper At The Gates Of Dawn. His songs were mostly short, eccentric, pop ditties.
Terrapin is taken from his solo album, The Madcap Laughs, and is a great example of his quirky style. David Gilmour frequently performs it in concert and the lesson looks more at his version, although they are very similar. The song uses mostly open and partial barre chords, and mixes in a little melody where we need some focused strumming.