The document discusses the key features of auxins including an aromatic ring, an aliphatic side chain with a carboxylic acid group, and a specific spatial configuration between the ring and chain. It also lists some common synthetic auxins like IBA and 4-Cl-IAA and describes how the widely used herbicide 2,4-D mimics auxin action to selectively kill broadleaf weeds over monocot grasses. However, the exact molecular mechanism for this selective activity between dicots and monocots is still not fully understood.