Reference: List of Blockchain Related Software
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A blockchain is a hash of hashes, which in turn can be hash of hashes, which in turn can be hash of hashes, etc. The hashes are secure hashes. The key phrase to search for is "Merkle tree".  A distributed blockchain is a blockchain, where the hashes are somehow distributed among different computers. The rest is implementation details of a particular blockchain implementation, including the various consensus related aspects, if the consensus is sought at all.