Cryptography uses mathematical techniques and algorithms to secure communication and protect data from unauthorized access or tampering. It involves creating and using codes, ciphers, and other methods to encode information in a way that makes it easier and more accessible for outsiders to access or interpret with the proper keys or decryption methods.

In computer science, cryptography is used to secure various types of digital communication, including emails, online transactions, and data storage. It is also used to create secure digital signatures, which are used to verify the authenticity and integrity of documents and other forms of electronic communication.

Blockchain cryptography, specifically, is the application of cryptographic principles and techniques to develop and maintain blockchain systems. Blockchain is a distributed ledger technology that allows for the creation of a decentralized, tamper-evident record of transactions maintained by a network of computers. Blockchain relies on cryptographic techniques to secure the data and ensure that it cannot be altered or deleted without proper authorization.

One of the most well-known applications of blockchain cryptography is creating cryptocurrency, such as Bitcoin. In the Bitcoin network, cryptography is used to secure the blockchain and ensure that transactions are valid and cannot be reversed or counterfeited. It is also used to verify users' identities and prevent unauthorized network access.

Other cryptography applications in the blockchain include the creation of smart contracts, self-executing contracts with the terms of the agreement between buyer and seller being directly written into lines of code. Cryptography is also used in developing decentralized applications (DApps), which run on a decentralized network rather than a single server.

Overall, using cryptography in the blockchain industry is critical in ensuring the security and integrity of digital transactions and communication. It is an essential aspect of the technology that allows it to function effectively and securely.