An MLS ID number is a number used by real estate agents to log into the Multiple Listing System (MLS). A realtor's MLS ID number is the same as a user name ID or a login ID.
The MLS links real estate agents and brokers through a network that allows them to easily view available listings. Real estate agents use the service to work on sales for their buyers and sellers within the same city or state or across the world. The goal of the MLS is to assure that compensation levels, such as commissions, are uniform and that specific information regarding properties, such as square footage, rooms, amenities and property size, is available for agents to access.