Navigating The Modern Ad Serving Stack, Part 3: Private Marketplaces (Deal ID)

Private marketplaces are made possible by a component of the RTB technology standard (OpenRTB) known as “Deal ID,” which allows publishers to take their inventory off the open auction of the public marketplace  and place it in an invitation-only area.
Since Deal ID is a component of the RTB tech stack, publishers who have an RTB exchange partner can leverage this technology without having to introduce a new vendor.
http://marketingland.com/navigating-modern-ad-serving-stack-part-3-private-marketplaces-deal-id-128234