SubID tracking is an affiliate marketing strategy used to add special identifiers, referred to as SubIDs, to affiliate links in order to make them amenable to thorough performance analysis. These identifiers allow marketers to track individual sources of traffic, ad placement, creatives, or campaigns, and have a better idea of which elements are driving conversions and revenue. Through the leveraging of SubID tracking, affiliates are able to optimize their strategies through data-driven decisions, improve ROI, and identify under-performing segments with ease for adjustment or elimination.