The acronym IDX means “Internet Data Exchange”. You can get the definition here or in a nutshell it means MLS (Multiple Listing Service) data (Las Vegas Homes) is pushed to individual agent’s or broker’s websites. Since the information is automatically pushed to the site and most is updated daily, you are getting the most accurate and up to date information on Las Vegas home listings.
There are many IDX providers and they can come in all shapes and forms. From no registration options to registration only options. I personally offer four different ways to search for Las Vegas Houses via IDX:
- No Registration for basic information (provided by my board, allows for rental home search also)
- Home Buyer’s Scouting Report
- iPhone to search by map via current location
- No Registration on my main website (located on right sidebar)
If you are scouring the planet and looking at places like craigslist, Realbird, Trulia or Zillow, you may be missing out! Those are NOT IDX listings but dependent on users (like individual Las Vegas real estate agents) to enter the information and keep it fully up to date. Our MLS has rules on keeping the information up to date in the MLS and does enforce via fines.
Las Vegas Home Sellers MAY opt out of the IDX system but they also opt out of other huge IDX fed sites such as Realtor.com and the major franchise sites + all the little guys that have IDX as a courtesy for their potential buyers. (HINT: If an agent says your site gets put on their big brand site that gets a gazillion hits a month, if you choose IDX with your listing, it will still go on said big brand site whether you list with that big brand or a small indy.)
The listing contract for Las Vegas Sellers allows you to opt out of other parts of internet marketing and IDX also and it looks like this:
So there are alternate choices to opt in to IDX but still retain a bit of privacy. One example of opting out of public address would be so that your neighbors don’t find out your home is listed.
I do encourage sellers to opt out of AVM sites (automatic estimated value ie Zillow or Corelogic) as those sites are not really all that accurate in the Las Vegas real estate climate currently. This is due to a large portion of sales that would be considered “not typical” due to trustee sales being recorded at the Clark County Recorder’s office.
NOW, as a Las Vegas buyer, you can see that it is incorrect that IDX is ALL MLS data. It is still prudent to interview Las Vegas agents that have MLS access so you can be put on an automated search to receive an email every time a new listing hits the market – just in case it has an IDX exclusion!
Best of luck on your Las Vegas home search or sale! I hope you have a better understanding of what IDX is – and what it is not 
RT @ReneeBLV: Las Vegas Buyers & Sellers: How the Acronym "IDX" Can Assist in Finding a Home or Sell Your Home http://bit.ly/e3tyAP