I was looking for buying a townhouse or small house in Ellicott City (MD). About 50% that I found on Zillow.com as "available to buy" were sold or under contract in reality. Finally I bought a townhouse in Dec 2012 for $290,000, however in Nov 2013, my townhouse was marked on the website as "Sold May 2013 for $318,000". Where does the site gain information about houses?