Whether you're looking to sell or buy a home, you will no doubt encounter the multiple listing service, or MLS.  This is, in many ways, the very lifeblood of the real estate business.  While numerous websites aggregate home listings through highly condensed versions of MLS listings, Realtor.com® is by far the most comprehensive, with 99% of all MLS-listed "for sale" properties in the U.S.  Home sellers can't post their home directly to the MLS, because access to this database is limited to licensed agents and brokers who pay for membership.  Once they have a client selling a home, they gather the necessary details such as the square footage, number of bedrooms, and other noteworthy attributes—as well as photos—then post a complete listing on their client's behalf.  When agents log in, they have access to a wealth of data that they can pass along to their clients—or just help them do their business better and more strategically.  Yes, the MLS seems like an invention of the modern age.  But, in fact, the term “multiple listing”—and the overarching concept behind it—was first coined in 1907.  Back then it described the old-timey practice in which real estate agents would gather regularly at offices or conferences to trade info about homes they were trying to sell, hoping this network could help connect them with buyers.  In 1908, the National Association of Real Estate Exchanges (the organization that later became the National Association of Realtors®) endorsed the use of this system by all agents.  It quickly caught on from there, evolving, stage by stage, into the modern system in use today—online and fully searchable by price, neighborhood, and home features.