IDX sites usually provide less detailed information than the full Realtor Multiple Listing Service, limiting the data to that which is deemed publicly accessible.
IDX implementations and standards have changed drastically over recent years, as brokers and agents utilizing IDX services along with companies proving IDX services have focused on the inherent ability to optimize websites with IDX-driven listing content. A variety of options for displaying IDX content on individual websites exist, including the practice of “truly embedding” IDX content into pages to iframe-driven implementations, which some consider a hidden implementation, since the true site delivering the IDX service is only framed into another website.
Policies around these implementations as well as IDX content on Social Media are a hot topic in many circles. A common and standard data exchange protocol for IDX information is the Real Estate Transaction Specification (RETS).