A short history of digital money: from eCash to Bitcoin

People tried to build digital money long before 2009. Looking at those attempts explains why Bitcoin is designed the way it is.

The double-spending problem

A digital file can be copied. If money is just a file, what stops someone from spending the same coin twice? For decades the only answer was a trusted central party — a bank or a payment company — that keeps the one true ledger.

eCash: privacy with a central operator

In the 1980s cryptographer David Chaum described "blind signatures", which let a bank sign a digital coin without seeing which coin it signs. His company DigiCash launched eCash in the 1990s. Payments could be private, but the system still depended on a central issuer, and DigiCash went bankrupt in 1998.

Hashcash: making work expensive

In 1997 Adam Back proposed hashcash, a way to fight email spam: before sending a message, a computer must find a value whose hash meets a target. Finding it takes work; checking it is instant. This idea — proof of work — later became the heart of Bitcoin mining.

b-money and bit gold

At the end of the 1990s and in the 2000s, Wei Dai (b-money) and Nick Szabo (bit gold) sketched systems where money is created by solving computational puzzles and records are kept by a group of participants rather than one company. Neither became a working network, but both are cited as important predecessors.

Bitcoin puts the pieces together

In 2008 a white paper published under the name Satoshi Nakamoto combined:

• proof of work to make rewriting history expensive;
• a chain of blocks linked by hashes;
• a peer-to-peer network that keeps the ledger without a central operator;
• a fixed issuance schedule written into the software.

The network started in January 2009. For the first time, the double-spending problem was solved without a trusted middleman.

After Bitcoin

Later projects explored programmable money (Ethereum), faster payments, privacy and stablecoins whose value follows a currency. Read more in What is Bitcoin? and What is Ethereum?.

History does not predict prices. It explains the design choices you see in today's networks.