When doomed stubs attack: blockchain voting and proof of work — Bitfield Consulting

Blockchain networks prevent double-spending through cryptographic hashing, where each block contains a hash of the previous block, creating an immutable chain. Nodes compete to compute the next valid block, with the longest chain representing consensus. Proof of work makes this computationally expensive by requiring hash values within specific ranges, deterring fraud through cost but consuming massive energy (Bitcoin uses 120+ TWh annually). Alternative approaches like proof of stake prioritize nodes with the most currency rather than computing power, though this raises concerns about plutocracy.