Bitcoin is a network that runs on a protocol known as the blockchain. While it does not mention the word blockchain, a 2008 paper by a person or people calling themselves Satoshi Nakamoto first described the use of a chain of blocks to verify transactions and engender trust in a network.2
The blockchain has since evolved into a separate concept, and thousands of blockchains have been created using similar cryptographic techniques. This history can make the nomenclature confusing. Blockchain sometimes refers to the original Bitcoin blockchain. At other times, it refers to blockchain technology in general, or to any other specific blockchain, such as the one that powers Ethereum.
Any given blockchain consists of a single chain of discrete blocks of information, arranged chronologically. In principle, this information could include emails, contracts, land titles, marriage certificates, or bond trades. In theory, any type of contract between two parties can be established on a blockchain as long as both parties agree on the contract. This takes away any need for a third party to be involved in any contract and opens up a world of possibilities including peer-to-peer financial products, such as loans or decentralized savings and checking accounts, wherein banks or any intermediary are irrelevant.
Blockchain’s versatility has caught the eye of governments and private corporations; indeed, some analysts believe that blockchain technology will ultimately be the most impactful aspect of the cryptocurrency craze.
In Bitcoin’s case, the information on the blockchain is mostly transactions. Bitcoin is really just a list. Person A sent X bitcoin to person B, who sent Y bitcoin to person C, etc. By tallying these transactions up, everyone knows where individual users stand. It’s important to note that these transactions do not necessarily need to take place between humans.
Bitcoin’s blockchain network creates vast possibilities for the Internet of things. In the future, we could see systems in which self-driving taxis or Uber vehicles have their own blockchain wallets. The passenger would send cryptocurrency directly to the car, which would not move until the funds were received. The vehicle would be able to assess when it needs fuel and use its wallet to facilitate a refill.
Another name for a blockchain is a “distributed ledger,” which emphasizes the key difference between this technology and a well-kept Word document. Bitcoin’s blockchain is distributed, meaning that it is public. Anyone can download it in its entirety or go to any number of sites that parse it. This means that the record is publicly available, but it also means that there are complicated measures in place for updating the blockchain ledger. There is no central authority to keep tabs on all Bitcoin transactions, so the participants themselves do so by creating and verifying “blocks” of transaction data. See the section on mining below for more information.
You can see the status of blocks, and their associated transactions, on sites. Such sites list the address identifier for the transacting parties, dates, the date on which the transaction took place, and the time of the transaction.3
The long strings of numbers and letters are addresses, and if you were in law enforcement or just very well informed, you could probably figure out who controlled them. It is a misconception that Bitcoin’s network is totally anonymous, although taking certain precautions can make it very hard to link individuals to transactions.