The process of appending additional identity signals to outgoing bid requests in real time, increasing the addressability of publisher inventory with more identifiers for buyers to match against. Signals include behavioral signals (content consumed, engagement depth, and recency and frequency of on-site actions), contextual signals (page-level topic, category, and keyword signals derived from content classification), demographic signals (characteristics like age, gender, and income data appended from first-party or third-party sources), device enrichment (device make, model, and OS metadata used to improve cross-device recognition), and geographic signals (location data including DMA, postal code, and household-level signals).