Hedera (distributed ledger)#Hedera Hashgraph

Hashgraph was invented in the mid-2010s by the American computer scientist Leemon Baird. Baird is the co-founder and chief technical officer of Swirlds, a company that holds patents covering the hashgraph algorithm.{{citation |title = Can hashgraph succeed blockchain as the technology of choice for cryptocurrencies? |url = http://www.thehindu.com/sci-tech/technology/can-hashgraph-succeed-blockchain-as-the-technology-of-choice-for-cryptocurrencies/article23348176.ece |work = The Hindu |date = 25 March 2018 }}{{citation |title = Hashgraph wants to give you the benefits of blockchain without the limitations |url = https://techcrunch.com/2018/03/13/hashgraph-wants-to-give-you-the-benefits-of-blockchain-without-the-limitations/ |work = TechCrunch |date = 14 March 2018 }} Hashgraph were described as a continuation or successor to the blockchain concept, which provides increased speed, fairness, low cost, and security constraints.{{Cite book|title=On the Move to Meaningful Internet Systems. OTM 2018 Conferences: Confederated International Conferences: CoopIS, C&TC, and ODBASE 2018, Valletta, Malta, October 22-26, 2018, Proceedings, Part 2|last1=Panetto|first1=Herve|last2=Debruyne|first2=Christophe|last3=Proper|first3=Henderik|last4=Ardagna|first4=Claudio|last5=Roman|first5=Dumitro|last6=Meersman|first6=Robert|publisher=Springer|year=2018|isbn=9783030026707|location=Cham|pages=281}}

Based on Hashgraph protocol, Hedera Hashgraph mainnet was launched in 2019.{{Cite web|url=https://www.computerworld.com/article/1657817/hadera-hashgraph-launches-mainnet-hopes-to-compete-with-global-business-networks.html|title=Hedera Hashgraph launches mainnet, hopes to compete with global business networks}} The Hedera white paper co-authored by Baird explained that "at the end of each round, each node calculates the shared state after processing all transactions that were received in that round and before," and it "digitally signs a hash of that shared state, puts it in a transaction, and gossips it out to the community."{{Cite web |last1=Baird |first1=Leemon |last2=Harmon |first2=Mance |last3=Madsen |first3=Paul |date=August 13, 2019 |title=Hedera: A Public Hashgraph Network & Governing Council |url=https://www.hedera.com/hh-whitepaper-v1.5-190219.pdf |url-status=dead |archive-url=https://web.archive.org/web/20201111192356/https://hedera.com/hh-whitepaper-v1.5-190219.pdf |archive-date=2020-11-11 |access-date=2024-04-23 |website=Hedera |edition=version 1.5}}

In 2020, Google Cloud joined Hedera Governing Council.{{Cite web|url=https://www.zdnet.com/article/google-cloud-joins-dlt-platform-hedera-hashgraphs-governing-council/|title=Google Cloud joins DLT platform Hedera Hashgraph's governing council|website=ZDNET}} A year later, EFTPOS joined the governing council.{{Cite web |url=https://www.theaustralian.com.au/business%2Ffinancial-services%2Feftpos-australia-joins-google-ibm-nomura-as-an-owner-and-member-of-the-hedera-governing-council%2Fnews-story%2Fc82d14969b3c7b232e194da7f23472e3?amp&nk=94a38a22c8a4b305d6097b4c75db7558-1739089651 |title=Eftpos Australia joins Google, IBM, Nomura as an owner and member of the Hedera Governing Council|first=Joyce |last=Moullakis |date=January 28, 2021}}

In September 2024{{Cite web |date=2024-09-16 |title=Introducing Hiero: Bringing Hedera's Core Network Software to Linux Foundation Decentralized Trust |url=https://www.lfdecentralizedtrust.org/blog/introducing-hiero-bringing-hederas-core-network-software-to-linux-foundation-decentralized-trust |access-date=2024-10-02 |website=www.lfdecentralizedtrust.org |language=en}} Hedera has transferred all source code of the Hedera Hashgraph to the Linux Foundation. The sources are now available as the open-source and vendor-neutral project Hiero.

Hedera Hashgraph is a public distributed ledger based on the Hashgraph algorithm.{{citation|title=How Hedera Hashgraph is building a fast and secure blockchain alternative|date=4 August 2018|url=https://venturebeat.com/2018/08/04/how-hedera-hashgraph-is-building-a-fast-and-secure-blockchain-alternative/|first=Dean |last=Takahashi|work=VentureBeat|access-date=20 March 2021}}{{Cite web|url=https://www.zdnet.com/article/eftpos-develops-micropayment-proof-of-concept-with-hedera-hashgraph/|title=Eftpos develops micropayment proof-of-concept with Hedera Hashgraph|website=ZDNET}} Hedera Hashgraph is developed by a company of the same name, Hedera, based in Dallas, Texas. Hedera was founded by Hashgraph inventor Leemon Baird and his business partner Mance Harmon, and Andrew Masanto, adding significant contribution to the team.{{Cite web |title=Hedera's Journey |url=https://hedera.com/journey |access-date=2024-01-31 |website=Hedera |language=en}} Previously, Hedera had an exclusive license to the Hashgraph patents held by their company, Swirlds. The Hedera Governing Council voted to purchase the patent rights to Hashgraph and make the algorithm open source under the Apache License in 2022.{{cite web |title=Hedera Governing Council Votes to Purchase Hashgraph IP,… |url=https://hedera.com/blog/hedera-governing-council-votes-to-purchase-hashgraph-ip-commits-to-open-source-worlds-most-advanced-distributed-ledger-technology |website=Hedera |language=en |date=19 January 2022}}

Hedera mainnet is maintained by governing council members which include companies such as Deutsche Telekom, IBM, FIS Global, and Tata Communications.{{Cite web|url=https://www.bizjournals.com/dallas/inno/stories/news/2020/02/19/google-joins-richardson-startup-hedera-hashgraphs.html|title=Google Joins Richardson Startup Hedera Hashgraph's Governing Council}}{{Cite web|url=https://www.zdnet.com/finance/blockchain/ibm-and-tata-join-dlt-platform-hedera-hashgraphs-governing-council/#google_vignette|title=IBM and Tata join DLT platform Hedera Hashgraph's governing council|website=ZDNET}}

Unlike blockchains, hashgraphs do not bundle data into blocks or use miners to validate transactions. Instead, hashgraphs use a "gossip about gossip" protocol where the individual nodes on the network "gossip" about transactions to create directed acyclic graphs that time-sequence transactions.{{Cite book|url=https://books.google.com/books?id=NqBiCgAAQBAJ&q=hashgraph+ledger&pg=PT42|title=Blockchain Revolution: How the Technology Behind Bitcoin Is Changing Money, Business, and the World|last1=Tapscott|first1=Don|last2=Tapscott|first2=Alex|date=2016|publisher=Penguin|isbn=9781101980156|language=en}} Each "gossip" message contains one or more transactions plus a timestamp, a digital signature, and cryptographic hashes of two earlier events. This makes Hashgraph form an asynchronous Byzantine Fault-Tolerant (aBFT) consensus algorithm.{{Cite book|title=Business Transformation through Blockchain, Volume 2|last1=Treiblmaier|first1=Horst|last2=Beck|first2=Roman|publisher=Palgrave Macmillan|year=2018|isbn=9783319990576|location=Cham|pages=98}}

It has been claimed that hashgraphs are less technically constrained than blockchains proper.{{citation |title = Can hashgraph unseat blockchain as the favoured tech for cryptocurrencies? |url = https://www.livemint.com/Technology/eYPTFc0yOSjQxhuo3TFWHO/Can-hashgraph-unseat-blockchain-as-the-favoured-tech-for-cry.html |work = Live Mint |date = 20 March 2018 }}{{cite web |title = Next-Generation Crypto-Ledgers Take the Block Out of Blockchain |url = https://www.bloomberg.com/news/articles/2018-02-14/next-generation-crypto-ledgers-take-the-block-out-of-blockchain |website = Bloomberg |access-date = 24 February 2018 }} Cornell Professor Emin Gün Sirer notes that "The correctness of the entire Hashgraph protocol seems to hinge on every participant knowing and agreeing upon N, the total number of participants in the system," which is "a difficult number to determine in an open distributed system." Baird responded that "All of the nodes at a given time know how many nodes there are."{{citation |title=Hedera Hashgraph Thinks It Can One-Up Bitcoin And Ethereum With Faster Transactions |url=https://www.forbes.com/sites/jeffkauflin/2018/03/13/hedera-hashgraph-thinks-it-can-one-up-bitcoin-and-ethereum-with-faster-transactions/ |work=Forbes |date=13 March 2018 }}

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