Know Your Customer, or KYC, is the set of regulated checks that banks, exchanges, and many online services must perform to verify who their customers are — collecting identity documents, addresses, and sometimes biometrics to prevent fraud and money laundering. It is a compliance obligation, but from an intelligence perspective it is also a concentration of high-quality identity data tied to real people.
For investigators, KYC matters in two directions. It is a mechanism that can de-anonymise otherwise pseudonymous activity — the point where a cryptocurrency address or online account connects to a verified legal identity, valuable for due diligence and financial intelligence. It is also a liability: KYC records are a prime target for breaches, and leaked KYC data exposes exactly the sensitive identity information the process was meant to protect.