A supply-side platform (SSP) is an advertising technology platform used by publishers to manage, sell, and optimize their available inventory of digital ad space. SSPs are also known as sell-side platforms and are a key part of the real-time bidding (RTB) process within programmatic advertising. SSPs allow publishers to connect their inventory to multiple ad exchanges and demand-side platforms (DSPs) simultaneously, enabling them to optimize yield by aggregating, consolidating, and managing their demand sources. SSPs provide the technology and resources that enable publishers to set brand safety guidelines, categories, and pricing, and then hold an auction that takes all of these factors into account, with the highest bidder winning the auction. SSPs also offer several benefits to publishers, including automated selling of inventory, brand safety, and insights on the value of their inventory for different advertisers. Some of the main features of an SSP include real-time bidding transactions, frequency capping, and relevancy.