Arenes are aromatic hydrocarbons. The term "aromatic" originally referred to their pleasant smells (e.g., from cinnamon bark, wintergreen leaves, vanilla beans and anise seeds), but now implies a particular sort of delocalized bonding. Aromatic hydrocarbons (or sometimes called arenes or aryl hydrocarbon) are hydrocarbons with sigma bonds and delocalized $$\pi$$ electrons between carbon atoms forming rings.