About 80 percent of all home buyers begin their quest online, according to the National Association of Realtors. Usually, they visit sites such as Realtor.com, which contain most of the listings available within a specified area. Those sites, however, usually answer only a few of the myriad questions that prospective buyers have about houses. They often don’t address subjects like: How is the neighborhood? Is it on a busy street? Is there any nearby place for the kids to play? Zillow is attempting to expand the conversations centered around the home listings by providing an online forum for exchanging that kind of information.