ZK blockchains refer to blockchain networks that incorporate zero-knowledge proof (ZKP) technology for enhancing privacy, scalability, and security. ZKP is a cryptographic protocol that enables transactions to be verified without the need for disclosing sensitive data or revealing identities. By utilizing this technology, ZK blockchains are able to process more transactions per second, provide a high level of privacy, and ensure data integrity. ZK rollups are a popular application of ZK technology, allowing for the off-chain aggregation of transactions before verification on-chain, which significantly increases the transaction throughput of Ethereum and other blockchain networks.