BITCOIN HISTORY

Background
Before bitcoin, several digital cash technologies were released, starting with David Chaum's ecash in the 1980s.[13] The idea that solutions to computational puzzles could have some value was first proposed by cryptographers Cynthia Dwork and Moni Naor in 1992.[13] The concept was independently rediscovered by Adam Back who developed Hashcash, a proof-of-work scheme for spam control in 1997.[13] The first proposals for distributed digital scarcity-based cryptocurrencies came from cypherpunks Wei Dai (b-money) and Nick Szabo (bit gold) in 1998.[14] In 2004, Hal Finney developed the first currency based on reusable proof-of-work.[15] These various attempts were not successful:[13] Chaum's concept required centralized control and no banks wanted to sign on, Hashcash had no protection against double-spending, while b-money and bit gold were not resistant to Sybil attacks.[13]

2008–2009: Creatseveral hacks or thefts from cryptocurrency exchanges.[41]

2020–present

Bitcoin price in US dollars
In 2020, some major companies and institutions started to acquire bitcoin: MicroStrategy invested $250 million in bitcoin as a treasury reserve asset,[42] Square, Inc., $50 million,[43] and MassMutual, $100 million.[44] In November 2020, PayPal added support for bitcoin in the US.[45]

In February 2021, Bitcoin's market capitalization reached $1 trillion for the first time.[46] In November 2021, the Taproot soft-fork upgrade was activated, adding support for Schnorr signatures, improved functionality of smart contracts and Lightning Network.[47] Before, Bitcoin only used a custom elliptic curve with the ECDSA algorithm to produce signatures.[48]: 101  In September 2021, Bitcoin became legal tender in El Salvador, alongside the US dollar.[4] In October 2021, the first bitcoin futures ETF, called BITO, from ProShares was approved by the SEC and listed on the Chicago Mercantile Exchange.[49]

In May and June 2022, the bitcoin price fell following the collapses of TerraUSD, a stablecoin,[50] and the Celsius Network, a cryptocurrency loan company.[51][52]

In 2023, ordinals, non-fungible tokens (NFTs) on Bitcoin, went live.[53] In January 2024, the first 11 US spot bitcoin exchange-traded funds (ETFs) began trading, offering direct exposure to bitcoin for the first time on American stock exchanges.[54][55]ion