Glossary
Mixer
A service that pools deposits from many users and lets them withdraw to different addresses, breaking the on-chain link between source and destination.
A mixer (or "tumbler") takes deposits into a common pool and releases the funds to fresh addresses provided by depositors. With enough volume and unpredictable timing, an outside observer cannot match any specific deposit to any specific withdrawal.
Mixers range from informal Bitcoin services (often custodial and scammy) to formal zero-knowledge protocols like Tornado Cash. Their status under sanctions and AML law is contested: the technology is neutral, but specific deployments have been sanctioned or prosecuted.