This article was originally published at [https://gist.github.com/joepie91/e49d2bdc9dfec4adc9da8a8434fd029b](https://gist.github.com/joepie91/e49d2bdc9dfec4adc9da8a8434fd029b).

Your blockchain must have *all* of the following properties: - It's a merkle tree, or a construct with equivalent properties. - There is no single point of trust or authority; nodes are operated by different parties. - Multiple 'forks' of the blockchain may exist - that is, nodes may disagree on what the full sequence of blocks looks like. - In the case of such a fork, there must exist a deterministic consensus algorithm of some sort to decide what the "real" blockchain looks like (ie. which fork is "correct"). - The consensus algorithm must be executable with *only* the information contained in the blockchain (or its forks), and no external input (eg. no decisionmaking from a centralized 'trust node'). If your blockchain is missing *any* of the above properties, **it is not a blockchain, it is just a ledger.**