zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Arguments of Knowledge) and zero-knowledge proofs (ZKPs) enhance privacy in crypto transactions by enabling users to prove the validity of transactions without revealing sensitive information. ZKPs allow one party to prove to another that they know a value (e.g., private transaction details) without disclosing the actual value. zk-SNARKs, a specific type of ZKP, make this process efficient by providing succinct proofs that are small in size and require minimal computational resources. This ensures that transaction details such as the sender, recipient, and amount remain private, while still validating the correctness of the transaction on the blockchain.