This is the latest in a series of 'Buyer's Guides' that feature questions to ask and options to consider before making a new purchase. See our previous guides to purchasing a CMA, CRM, Document and Transaction Management, Electronic Signature, and Ad Network.

What are IDX and VOW?

We defined these terms in our popular article "Listing Syndication Definitions." Borrowed from that article, here is a simple definition of IDX and VOW.

• IDX or Internet Data Exchange is sometimes referred to as "broker reciprocity." IDX is a set of business rules that allows brokers (and agents) to display another participating brokers listings on their website; in exchange, they agree to allow other participating brokers to display their listings. Brokers who agree to the IDX rules receive a data feed from the MLS containing the active listings for all participating brokers in the MLS marketplace for use on their site. Under no circumstances can the IDX data of another broker's listings be provided to any non-MLS participant. IDX rules also include very specific listing display requirements for each participating broker; for example, usually the listing brokerage name is required to display alongside the listing.
• A Virtual Office Website (VOW) is a broker website that allows the public to register in order to view every bit of data that is in the MLS (with the exception of confidential information, such as showing instructions). It is the registration requirement and the more complete information that sets a VOW apart from an IDX website. However, like IDX, it allows brokers to share data from the MLS with consumers. VOW data fields may include days on market, original list price and changes over time, sold data, and other fields that are not allowed to be displayed through IDX, and that are not included in a data feed for syndication.