A Multiple Listing Service (MLS), is a group of real estate brokers who pool their listings to maximize exposure of properties and to increase sales. A broker member of an MLS who obtains a listing submits it to the MLS database. He or she is the "Listing Broker". The listing information is immediately available on the MLS database, which agents use to search for properties to show their buyer. 

Access to an MLS, then, greatly increases the available "inventory" of properties for an agent and enhances their chances of finding a suitable property for a potential buyer. The broker who finds the buyer is the "Selling Broker" or "Buyer Broker".  Their incentive is that they will be paid a commission by the seller, which is disclosed in the MLS, traditionally 3%.

One advantage for the seller in listing their property in the MLS is accessing those buyers who work exclusively through a real estate agent and don't look for the "for sale by owner". Additionally, the MLS databases are downloaded to public sites such as Realtor.com and hundreds of real estate company websites, local and national.

In order to be a member of an MLS and list properties in the system, one must be a licensed real estate broker.  Agents hang their real estate license with a broker and then can list properties in the MLS under that brokerage.

By using the power of the Multiple Listing Service, the flat listing fee program increases the seller's chances of selling their property in the least amount of time for the most money.