To a full node running the standard Bitcoin software, any given bitcoin is identical in nature to any other. However, because the blockchain is a public record, and real-life identities may be linked to transactions/addresses, some Bitcoin users may choose to treat certain bitcoin differently than others. For example, a transaction linked to criminal activity may not be accepted by some users due to its transaction history. Under certain circumstances though, it is possible to break the link between real-life identities and specific UTXO histories. This can allow users to regain previously lost transaction privacy and restore full fungibility.