Hash
A fixed-length alphanumeric string produced by passing data through a cryptographic hash function (like SHA-256). Hashes are one-way functions — they can convert any input into a unique fingerprint, but the original data cannot be recovered from the hash. Hashing is fundamental to blockchain security, mining, address generation, and data integrity verification.
“Bitcoin uses SHA-256 hashing. Even changing a single character in a document produces a completely different hash, making it easy to detect any tampering with blockchain data.”
Hash Rate
The total combined computational power being used to mine and process transactions on a Proof of Work blockchain, measured in hashes per second. A higher hash rate means greater network security because it becomes more expensive for an attacker to gain majority control. Hash rate is a key indicator of mining activity and network health.
Mining
The process of using computational power to validate transactions and add new blocks to a Proof of Work blockchain. Miners compete to solve a cryptographic puzzle (finding a hash below a target difficulty), and the first to succeed earns the block reward plus transaction fees. Mining secures the network by making it prohibitively expensive to attack.
Block
A collection of transactions bundled together and permanently added to the blockchain. Each block contains a timestamp, transaction data, a reference (hash) to the previous block, and a nonce. This chaining of blocks through cryptographic hashes is what makes the blockchain tamper-resistant.
Merkle Tree
A data structure where every leaf node contains a hash of a data block and every non-leaf node contains a hash of its child nodes, forming a tree that culminates in a single root hash (the Merkle root). Merkle trees allow efficient and secure verification that specific data is included in a large dataset without downloading the entire dataset — a property essential to blockchain scalability and light client operation.