Cross-Domain Tracking is analytics configuration that preserves user and session identity across related domains.
It matters because analytics turns marketing activity into decisions. Without clear measurement language, teams may misread performance, overvalue the wrong channels, or miss the actions that actually drive revenue.
Example
A visitor moves from a main website to a related booking domain. Correct cross-domain configuration can help preserve the intended journey when supported, while incompatible tags or missing linker information can create a new apparent referral or session.