Zcash cryptocurrency originated from a project called Zerocoin. This project originally focused on the improvement of anonymity in the bitcoin site.
The protocol has then been perfected and transferred to Zcash cryptocurrency. Transactions of this cryptocurrency are published in blockchain. However, users can use possibility to hide the sender as well as the receiver and the amount, that has been sent. All transactions could be made visible for audit purposes. This is possible for all participants of the transaction. It can be used in cases, where there is a need to prove the payment successful.
The transaction detail however does not contain information about origin, destination or the sent amount. Zero-knowledge proof technology is used to ensure validity of the transaction. This is a technology which enables one side to prove to the other side that the content is valid without the need to transfer any information about the transaction, except the fact, that it is truly valid.
This cryptocurrency also uses Equihash algorithm, which is a proof-of-work. It has, as well as bitcoin, limited quantity of 21 million units. Even though sites aim mainly for anonymity, the developer team issued statement in which stated, that Zcash has not been created in order to enable illegal activities.