Multiple Listing Service (MLS)

The MLS is a regional database of properties listed for sale, populated by member real estate brokerages. There isn't a single national MLS, there are roughly 600 regional MLS systems across the US, each covering a specific market or set of counties. Most listings show up on consumer-facing sites (Zillow, Realtor.com, Redfin) through licensing arrangements with the regional MLS.

How it works: when a brokerage takes a new listing, they enter it into the local MLS database with property details, photos, list price, and showing instructions. Other member brokerages can see the listing immediately and present it to their buyer clients. The MLS also includes historical data: closed sales prices, days on market, list-price-to-sale-price ratios. This is where listing agents pull comparable sales for pricing analysis.

Why it matters: the MLS is the primary distribution channel for residential listings. A property "on the market" without being in the MLS is much less visible, most buyers' agents and most consumer sites won't know about it. Off-MLS listings (sometimes called "pocket listings") trade reach for privacy or controlled exposure, with NAR rules now restricting how widely they can be marketed.

Common gotcha: post-2024 NAR settlement, buyer-side compensation can no longer be displayed in the MLS. Buyer's agents have to look up offered compensation through other channels, typically by calling the listing agent directly. The change has shifted some of how compensation conversations happen at the start of buyer-property engagement.