I understand that blockchain technology works for cryptocurrency. But I don't get why it should be used in private sector.

For example, I often read that it is useful to monitor the supply chain of food. But why is that? If a company uses blockchain technology for that, how does it work?

From my understanding, in that case it is hard to get a distributed blockchain. But with a non-distributed blockchain, I only see disadvantages. Why not use a good old standard database in such cases?

Am I missing something?

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    $\begingroup$ Why is the question tagged "cryptocurrency" if it's about blockchain not for cryptocurrency? And what about giving a definition of "blockchain"? The one I know is on the tune of: collection of smurfs including a signature or hash of part of itself and optionally other smurfs; but that's hardly precise enough for orderly discussion. Please also define "non-distributed". $\endgroup$
    – fgrieu
    May 8 at 10:04
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    $\begingroup$ I’m voting to close this question because it's about non-cryptographic aspects of blockchains. $\endgroup$
    – Maeher
    May 9 at 13:12
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    $\begingroup$ wow... very helpful community here. Sorry, for the wrong tag. I see it is not directly related to cryptocurrency, but I thought it is distantly related. And I was not aware that this stack exchange is strictly and only used for direct cryptographic aspects. Since the blockchain is based on cryptography, I thought there are people here that might be interested in this topic. So sorry again for bothering you. About the one question: By "non-distributed" I mean, that companies seem to use blockchain without the distributed ledger concept. So just one blockchain on their local computer. $\endgroup$
    – DanielG
    May 9 at 19:25
  • $\begingroup$ This is a cryptography Q&A community, NOT a cryptocurrency Q&A community. We allow anything having to do with the cryptographic aspects, including questions about the cryptography of blockchains. But the currency, economic, social, etc, aspects are off-topic. Also, there's no consensus anywhere on whether Merkle trees without a distributed consensus mechanism are even blockchains. EG git is a blockchain to some people, and not to others. It's not a well-defined term and becomes redundant if you allow centralized consensus. $\endgroup$ May 10 at 17:25

Why not use a good old standard database in such cases?

Am I missing something?

No; you understand it perfectly well! It's nothing more than a particularly strange form of data integrity assurance (that, as you quickly realize, is trivially bypassed if not distributed across multiple nodes). If you're not using it as a resistance to adversarial peers, and you're not using it for consensus-building purposes, then there's little benefit to be wrung from prefacing each $\text{block}_n$ with $H(\text{block}_{n-1})$.

Even distributed systems such as highly-available and fault-tolerant hypervisors that have to "solve" the Two Generals Problem accomplish their task perfectly fine with non-blockchain-based consensus algorithms.

(However, as the commenters note, this is much more of a systems engineering question than a cryptographic one.)

I will amend this answer to note that Merkle trees per se can be useful in situations where you require, for instance, the public to be able to easily audit or assure themselves that some log has remained append-only, such as in the Certificate Transparency security addition to HTTPS. But (again a nod to Peregrinus) these aren't "blockchains"* since they're not being leveraged for consensus: the scheme itself imposes no restrictions on the whole thing being rewritten; all the auditors can do is sound the alarm if they see a fork in the tree.

(*As evidenced by the fact that a quick search turns up a whole host of schemes proposing blockchain-based augmentations of CT.)

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    $\begingroup$ Every time I see people pushing "blockchain" as the hammer to things that aren't even nails, I'm reminded of this fictional vignette -- Chrysus, LLC had started as joke… Our primary ambition was to persuade venture capitalists to pay for a high-rise office and a high-end coffee machine. I knew the right kind of people and I knew how to erect a Potemkin village out of the latest buzzwords. Getting money is easy, doing something useful with it is hard… $\endgroup$ May 10 at 17:15
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    $\begingroup$ I'd add a note that Merkle Trees are the core data structure of a "blockchain". Indeed, a blockchain is just a Merkle Tree with a "cannonical" branch to a current leaf node. With a distributed consensus algorithm, you can get a cryptocurrency. With centralized consensus, you can get something like git. But most of the "private blockchains" could just as well be databases, and add nothing except a way to siphon off investor's money. $\endgroup$ May 10 at 17:29

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