So starts the question. What is an IDX, internet data exchange and why would you want to use one?
IDX systems correlate to Real Estate and the rendering of Listings that populate the Local Boards of Realtors, AKA: Multiple Listing Service MLS.
When you are searching for real estate that is for sale, you probably have heard of Homes.com, Realtor.com, Trulia.com, Redfin.com and others of the Large Real Estate Mega search websites.
In fact, if you are not looking at the Google Local Business ads, you will see these mega sites populating the tops of the Search Engines.
First, we agents can pay a fee to join those Real Estate Mega Sites and get leads, personal information from those of you searching.
Second, most of those systems don't have all of the listings. Some are fed by the agent's themselves. Some don't update as often as a Local IDX provider. Some have only been built so they can earn the "owner" of the website the most money possible.
I think I just covered more than "second", I had three additional points in the above sentence.
Bottom Line, Local Websites, advertising and utilizing the Internet Data Exchange are the strongest, most accurate and the most updated systems available for Real estate searches.