A Multiple Listing Service (MLS) is a local database of homes, commercial properties and land for sale. The MLS is owned and maintained by real estate brokers and agents in the area—and properties can only be listed by licensed real estate professionals who have paid fees to join the MLS organization.

When a property is listed on the MLS, its description and photos are entered into the MLS database. From there, real estate websites and other real estate professionals can access the information. In fact, most of the properties you see on popular real estate websites are collected from MLS databases.

This is why the Flat Fee MLS service is recommended so highly: It gives homeowners inexpensive options for selling. And it gives their property the exposure and attention it wouldn't have in the "For Sale By Owner" model.