How Bitcoin Works

 How exactly to categorize Bitcoin is a matter of controversy. Is it a type of currency, a store of value, a payment network, or an asset class?

Fortunately, it's easier to define what Bitcoin actually is. It's software. Don't be fooled by stock images of shiny coins emblazoned with modified Thai baht symbols. Bitcoin is a purely digital phenomenon, a set of protocols and processes.

It is also the most successful of hundreds of attempts to create virtual money through the use of cryptography, the science of making and breaking codes. Bitcoin has inspired hundreds of imitators, but it remains the largest cryptocurrency by market capitalization, a distinction it has held throughout its decade-plus history.

(A general note: According to the Bitcoin Foundation, the word "Bitcoin" is capitalized when it refers to the cryptocurrency as an entity, and it is given as "bitcoin" when it refers to a quantity of the currency or the units themselves. Bitcoin is also abbreviated as BTC. Throughout this article, we will alternate between these usages.)

The Blockchain

Bitcoin is a network that runs on a protocol known as the blockchain. A 2008 paper by a person or people calling themselves Satoshi Nakamoto first described both the blockchain and Bitcoin, and for a while, the two terms were all but synonymous.

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​.

The basics of blockchain technology are mercifully straightforward. Any given blockchain consists of a single chain of discrete blocks of information, arranged chronologically. In principle, this information can be any string of 1s and 0s, meaning it 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. This 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 is irrelevant.

Though Bitcoin's current goal is to be a store of value as well as a payment system, there is nothing to say that Bitcoin could not be used in such a way in the future, though consensus would need to be reached to add these systems to Bitcoin. The main goal of the Ethereum project is to have a platform where these "smart contracts" can occur, therefore creating a whole realm of decentralized financial products without any middlemen or the fees and potential data breaches that come along with them.

This 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, though, 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.

Anything can access and use the Bitcoin network, and your ethnicity, gender, religion, species, or political leaning is completely irrelevant. This 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, for example, that 15N3yGu3UFHeyUNdzQ5sS3aRFRzu5Ae7EZ sent 0.01718427 bitcoin to 1JHG2qjdk5Khiq7X5xQrr1wfigepJEK3t on Aug. 14, 2017, between 11:10 and 11:20 a.m. 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.