Bitcoin’s blockchain is the first ever organizationally decentralized and logically centralized log.
It is a log, not a database, yet it can be used as a master in a master-slave design pattern, where the slave is a normal SQL or NoSQL database. It is the first log that is highly tamper resistant. Never before have we had security as such a dominant design goal. In this age of hackers and government indiscretion, the blockchain can be used as a foundation of a new software stack.
To explain the above statements:
In the past, organizational centralization was required and with it an absolute trust that the transactions will be preserved unchanged, and will be properly sequenced and timestamped. We trust banks, government agencies and e-commerce sites among many others to provide such guarantees. Blockchain’s organizational decentralization greatly reduces the trust needed and achieves these guarantees on a global scale.
In the past decentralized systems were hard to make compatible. But blockchain is logically centralized, which makes it a great way to achieve sharing and compatibility between applications.
Blockchain is much less than a database, as it does not allow efficient searching and filtering. It also does not allow data to be modified. Yet we can import transactions from the chain into a normal database. A blockchain explorer, like blockchain.info and a commercial API, like chain.com, is in fact a slave database to the blockchain.