Blockchain is a decentralized system that is used to record transactions across many computers. It's secured from Cyber attacks and equipment destroy because stored data is available worldwide on a lot of computers and isn't stored on a single one. All computers automatically block any attempt that is directed to manipulation with data.
I don't think that Blockchain is only a decentralized system, as it was discussed that blockchain can be both a decentralized and centralized system depending on the way it was implemented.
A blockchain can be either centralized or decentralized. It is important, however, that decentralized not be confused with distributed. While a blockchain is inherently distributed (meaning that many parties hold copies of the ledger), it is not inherently decentralized.
So where can Blockchain Technologies be valuable?
I'll give you one example and that's a land registry, that I'll explain:
The benefits of implementing of blockchain technologies in land title registry are record reliability and a boost of security. BC technologies make registry transactions more accessible, more transparent and much more secure. It's impossible to delete, edit or manipulate with data that's stored on Blockchain. The authenticity of records is verified by the identical hashes available on Blockchain and on a website of land registry (hash is a combination of symbols that are unique for each document).
I think the blockchain can be manipulated or hacked.
Here is one example:
This criticism is most easily addressed by pointing to the vulnerability of public blockchains themselves. Take, for example, the Ethereum blockchain, which suffered a devastating exploit in June 2016. Someone found a coding loophole in a smart contract called “The DAO”, in which almost $250 million had been invested, and began draining its funds at speed. While this clearly violated the intentions of the contract’s creators and investors, its terms and conditions relied on the mantra that “code is law”. Law or not, less than a month later, the Ethereum software was updated to prevent the hacker from withdrawing the cryptocurrency “earned”.
So blockchain is used for anti-corruption systems? Something that needs to be done so nobody can’t be bribed. Hmm actually that can’t be the case because systems are made on purpose to be altered
I strongly agree with this one. There is no such thing as perfect immutability especially a system that can be modified anytime.
As of the value of Blockchain, I got no idea how much it worth.