What are Heads and Complements?
Every sentence has heads and their complements essentially, then, what are heads, and what are complements? Heads mean certain parts which play the most important role and also determine the characteristic of the phrases in sentence. For example, let’s think about the adjective phrase within the sentence ‘Mary is fond of Bill’. To describe the AP part with a syntax tree. :
You can see the AP is made of the adjective ‘fond’ plus the PP ‘of Bill’.