What is an Ur?

Bitcoin is both a cryptocurrency and an electronic payment system^[14]:3invented by an unidentified programmer, or group of programmers, under the name of Satoshi Nakamoto.^[15] Bitcoin was introduced on 31 October 2008 to a cryptography mailing list,^[16] and released as open-source software in 2009.^[17] The identity of Nakamoto remains unknown, though many have claimed to know it.^[15] The system is peer-to-peer, and transactions take place between users directly, without an intermediary.^[14]:4 These transactions are verified by network nodes and recorded in a public distributed ledger called the blockchain,^[18] which uses bitcoin as its unit of account. Since the system works without a central repository or single administrator, the U.S. Treasury categorizes bitcoin as a decentralized virtual currency.^[11] Bitcoin is often called the first cryptocurrency,^[19][20][21] although prior systems existed,^{[note 4]} and it is more correctly described as the first decentralized digital currency.^[14][25]Bitcoin is the largest of its kind in terms of total market value.^[26]