The Bitcoin White Paper was published by Satoshi Nakamoto in 2008; the first Bitcoin block got mined in 2009. Since the Bitcoin protocol is open source, anyone could take the protocol, fork it (modify the code), and start their own version of P2P money. Many so-called altcoins emerged and tried to be a better, faster or more anonymous than Bitcoin. Soon the code was not only altered to create better cryptocurrencies, but some projects also tried to alter the idea of blockchain beyond the use case of P2P money.  

The idea emerged that the Bitcoin blockchain could be in fact used for any kind of value transaction or any kind of agreement such as P2P insurance, P2P energy trading, P2P ride sharing, etc. Colored Coins and Mastercoin tried to solve that problem based on the Bitcoin Blockchain Protocol.

The Ethereum project decided to create their own blockchain, with very different properties than Bitcoin, decoupling the smart contract layer from the core blockchain protocol, offering a radical new way to create online markets and programmable transactions known as Smart Contracts. Private institutions like banks realized that they could use the core idea of blockchain as a distributed ledger technology (DLT), and create a permissioned blockchain (private or federated), where the validator is a member of a consortium or separate legal entities of the same organization.

The term blockchain in the context of permissioned private ledger is highly controversial and disputed. This is why the term distributed ledger technologies emerged as a more general term.

Private blockchains are valuable for solving efficiency, security and fraud problems within traditional financial institutions, but only incrementally. It’s not very likely that private blockchains will revolutionize the financial system.

Public blockchains, however, hold the potential to replace most functions of traditional financial institutions with software, fundamentally reshaping the way the financial system works.