Aromatics (or Benzene) are a special case of a cyclohexene. This cyclohexene alternates (all the way around) between double and single bonds. The structure has resonance so one configuration (e.g. single-double-single) can spontaneous switch/alternate (e.g. double-single-double) back and forth.
When the benzene ring is a substituent, it is called a phenyl group (not to be confused with phenol, a benzene ring with a hydroxy substituent making it an alcohol).
Aromatics do not easily undergo addition reactions, but rather substitution.
Common reactions include: halogenation, nitration, and sulfonation.
