A mining algorithm is the specific set of cryptographic rules and computations that proof-of-work (PoW) miners follow to compete for the right to add a new block to a blockchain. It defines how transactions are packaged into a candidate block and what kind of mathematical puzzle must be solved to make that block valid.
How a mining algorithm works in PoW
In most PoW networks, the “puzzle” is based on hashing, repeatedly running a candidate block header through a hash function while changing a small value (often called a nonce) until the output meets the network’s difficulty requirement. The algorithm determines the exact hash function used, the data that must be hashed, and how difficulty is expressed. When a miner finds a valid result, other nodes can quickly verify it, then accept the block and build on top of it.
Examples and why different algorithms exist
Different cryptocurrencies choose different mining algorithms to shape security and miner participation. Bitcoin uses SHA-256, which has led to specialized ASIC hardware dominating mining. Litecoin uses Scrypt, which was designed to be more memory-intensive, initially making ASIC development harder. Monero’s RandomX aims to favor general-purpose CPUs to reduce hardware centralization. Ethereum previously used Ethash while it was PoW, before moving to proof of stake.
Mining algorithms also influence a network’s resilience to certain threats. Hashing methods must remain cryptographically strong so attackers cannot cheaply find collisions or shortcut the work. Networks may change or tweak algorithms to respond to emerging hardware advantages or security concerns.
A mining algorithm matters because it directly impacts a blockchain’s security model, decentralization, hardware landscape, and the cost of attacking the network, all of which shape trust in the cryptocurrency ecosystem.