Retail Electric Service (RES) is a type of electricity service that is provided by a retail electric provider (REP) to residential and commercial customers. This type of service allows customers to purchase electricity from a REP at a rate that is lower than the rate charged by their local utility. The REP is responsible for purchasing electricity from the wholesale market and then reselling it to the customer at a lower rate. This type of service is becoming increasingly popular as customers look for ways to save money on their electricity bills.