Every person, cooperative, corporation, municipal corporation, company, association, joint stock company or association, firm, partnership, individual, or other entity, their lessees, trustees, or receivers appointed by any court whatsoever, that offers electric power or energy for sale, lease or in exchange for other value received to one or more retail customers, or that engages in the delivery or furnishing of electric power or energy to such retail customers, and shall include, without limitation, resellers, aggregators and power marketers, but shall not include electric utilities (or any agent of the electric utility to the extent the electric utility provides tariffed services to retail customers through that agent).

Is someone other than an Illinois electric utility that offers electric power or energy for sale, lease or in exchange for other value received, or that engages in the delivery or furnishing of electric power or energy, to one or more retail customers.

An entity, other than an Illinois jurisdictional utility which sells electricity to Retail Electric Customers in Illinois. ARES must be certified by the Illinois Commerce Commission.