A hash is the result of a mathematical function that turns any data into a string of characters of a fixed length. Hashing underpins the security of the blockchain and protects transactions against tampering.

SHA-256 is a cryptographic hash function that underlies the Bitcoin protocol and a number of other coins. It turns data into a unique fingerprint of fixed length.

Cryptography is the science of methods for protecting information by means of encryption. It ensures confidentiality and data integrity and underlies the operation of all cryptocurrencies.

A cryptographer is a specialist in the field of cryptography who develops and analyzes methods of encryption and data protection. Their work underlies the security of blockchain systems.

ECDSA is a digital signature algorithm based on elliptic curves that allows the owner of a private key to confirm the right to dispose of coins. It is precisely what protects transactions in Bitcoin and many other networks.