The Multiple Listing Service, or MLS, is a database that contains all the real estate listings in a given area. The only listings not included in this database are those that are for sale by owner. The common database allows real estate agents and home buyers to see all properties available. It also gives them search capabilities to narrow down the list of potential properties to those which meet the buyer's criteria. Let's say a buyer wants a 3-bedroom, 2-bath home with a list price of between $150,000 and $200,000, in the towns of Smithtown or Johnsonville. The real estate agent can go into the MLS and make a search using those parameters. A short list of properties will come back meeting those criteria. This makes it easy for the agent to find properties that meet the buyer's needs and budget.