Definition
OPSEC — operational security — is the discipline of protecting yourself by controlling the small pieces of information that, taken together, would let an adversary harm you. The term comes from military practice, where it described keeping individually harmless facts (a shipping schedule, a unit's location) from being assembled into a useful intelligence picture. Applied to digital and financial privacy, OPSEC is less about any single tool and more about consistent habits.
It is a process, not a product
Strong encryption, a hardware wallet, or a VPN can all be undone by behavior: reusing an identifying username, posting a photo with revealing metadata, bragging about holdings, or linking a pseudonymous identity to a real one through a careless payment. Good OPSEC means compartmentalizing identities, minimizing what you reveal, and assuming that anything published is permanent and correlatable. The goal is to deny an adversary the connecting threads, not to achieve impossible perfect secrecy.
Why Bitcoiners care
Bitcoin's transparency makes OPSEC unusually concrete. The blockchain is a permanent public ledger, so an address linked to your identity can expose your balance and history forever — which in turn creates physical risk. Sensible OPSEC for holders includes never disclosing amounts, avoiding address reuse, separating spending and savings, and keeping the fact that you hold Bitcoin out of public conversation entirely. The cheapest defense against a Wrench Attack is making sure no one knows there is anything to coerce.
OPSEC is most effective when grounded in a written Threat Model, since you cannot protect against threats you have not named.
In Simple Terms
OPSEC — operational security — is the discipline of protecting yourself by controlling the small pieces of information that, taken together, would let an adversary…