What is blockchain?
Blockchains are a particular type of ‘distributed ledger’ technology. At their core is a shared database that is organised as a list of ‘blocks’, with the constraint that an additional block of data is appended to the ledger only if a majority of nodes ‘agree’ that it is valid.
Agreement between multiple nodes about the validity of a block is derived via a ‘consensus mechanism’, of which there are several types. The new block is cryptographically ‘chained’ to the previous block that was added to the blockchain, which was chained to the block before it, and so on, all the way to the first block (the genesis block). Hence the name ‘blockchain’.
As blocks are only added to the blockchain with the consensus of independent nodes, there is no single point of failure through which the blockchain’s data can be corrupted. This makes unauthorised alterations significantly more difficult than they may be with traditional ledgers, which can be modified by a single trusted authority.
What’s in a ‘block’?
Information in Blockchain systems is added in ‘blocks’
The header includes metadata, such as a unique block reference number, the time the block was created, and a link back to the previous block.
The content typically includes a validated list of transactions made, their amounts, and the addresses of the parties to those transactions, along with digital assets and instruction statements. 
The blockchain opportunity for Australia
There are opportunities across our economy which can be seized and enabled by the use of blockchain technology: to create jobs, to create new economic growth, to save businesses money, and to improve our overall productivity. In addition, the combination of blockchain technology with other technologies, and the digital data underpinning blockchains, can add enormous additional economic value.
With broader application, Gartner predicts that blockchain will generate an annual business value of over US$175 billion by 2025 and in excess of US$3 trillion by 2030.  By 2023, blockchain will support the global movement and tracking of US$2 trillion worth of goods and services annually.  Within the financial services industry alone, analysts predict blockchain will save US$15–20 billion annually by 2022.  The costs to Australian food and wine producers of direct product counterfeiting and substitution, was estimated to be over AU$1.68 billion in 2017 alone.  Blockchain solutions can help to address this issue.
There is growing interest and investment in blockchain as a decentralised, peer-to-peer solution with the potential to deliver significant cost savings. Many people now have lower trust in social and traditional media, banks and governments to report the truth, protect privacy, and act in the interests of everyday people. Given this context, blockchain and other decentralised technologies may increasingly be preferred to traditional intermediaries.
Blockchain’s specific features make it an attractive option for conducting transactions and maintaining records, with potential applications across many sectors of the economy such as finance, trade, health, energy, water, resources, agriculture and credentials.
There are potential applications in both existing and emerging industries—from provenance, registries, energy and water trading, to blockchain for courts of law and spacecraft systems. Transactions facilitated by blockchain could open up new horizons for global trade and become the next step in the evolution of monetary systems. 
In Sectoral opportunities, the Roadmap lists a number of sectors where blockchain shows strong potential. It showcases the agricultural sector with a wine export example; the ‘trusted credentialing’ sector with an education example; and the identity sector with a ‘Know Your Customer’ checks example.
While there are significant opportunities for blockchain technologies, some use cases are more suited to blockchain than others. As the United States (US) Department of Homeland Security (DHS) notes:
Blockchain is best suited for use cases requiring at least three of the following: data redundancy; information transparency; data immutability; and a consensus mechanism. If only one or two are required then blockchain may work, but there are likely simpler or cheaper ways to solve the problem. 
Case Study: ASX & CHESS
ASX Limited is implementing a blockchain-based solution as the post-trade infrastructure for Australia’s equity market. The Clearing House Electronic Subregister System (CHESS), developed by ASX over 25 years ago, is currently the core system used by ASX to perform clearing, settlement and other post-trade services for the Australian equity market.
In 2015, ASX started a process to evaluate replacement options for CHESS. ASX commenced stakeholder consultation in 2016 to gain a better understanding of the new functionality and services that users of CHESS would like delivered by the replacement system. Dominic Stevens, ASX Managing Director and Chief Executive Officer, announced in late 2017 that, following careful examination:
We believe that using [blockchain] to replace CHESS will enable our customers to develop new services and reduce their costs, and it will put Australia at the forefront of innovation in financial markets  .
In 2019, ASX started customer development and testing for software vendors and in-house systems connected to CHESS in a dedicated customer development environment. The blockchain solution is currently estimated to go live in the first half of 2021.
The blockchain landscape in Australia
An analysis of 138 blockchain activities in Australia conducted by CSIRO’s Data61 (the data and digital specialist data services arm of CSIRO), and published in April 2019, shows a general upwards trajectory, with most of this activity coming from small-to-medium sized businesses in New South Wales and Victoria. Although the majority of activities were recorded within capital cities, there were some examples of regional blockchain activities. For instance, over 30 businesses in the Central Queensland towns of Agnes Water and Seventeen Seventy are now accepting cryptocurrency as a form of payment, designed to appeal to international tourists in the niche market of crypto-funded travel.
The leading industry for blockchain activities in Australia is financial and insurance services, followed by professional, scientific and technical services, and retail trade (see Figure 1).
Figure 1: Share of Australian blockchain activities, by Industry
Around 93% of blockchain activities have been undertaken by small-to-medium sized organisations with 1 to 200 employees, with a growing share of start-ups in Australia identifying with the blockchain industry—up from 3.4% in 2016 to 8.1% in 2018. Analysis of blockchain activities also demonstrates that Australia is home to a number of world-first blockchain applications, which include bonds operations; smart programmable money; a national blockchain system and international standards; as well as industry-specific trials in energy, agriculture and the public sector. 
Australia ranks sixth internationally in blockchain-related patent filings. There are currently 49 patent families, which are defined as a set of patents taken in various countries to protect a single invention, that address issues ranging from the data-processing side of the technology (encryption, transmission) to its applications in payment systems, administration and financial services. 
The Australian Government has invested in a wide range of blockchain-related activities to date. Funding has included support for government, private sector and university research, innovation and collaboration, through programs such as Austrade trade missions; the Entrepreneur’s Programme; Australian Research Council Grants; and Business Research and Innovation Initiative pilots. The government has also provided funding to Standards Australia to enable Australia to lead the development of international standards for blockchain and it has committed to the development of this Roadmap, in close collaboration with industry and universities.
The Government’s investments have been improving blockchain technology; demonstrating opportunities and use cases; and helping businesses bring blockchain products to market.
Figure 2: Example of how blockchain works
Figure 3: Blockchain myths busted
Myth: Blockchain is bitcoin
It may have been Bitcoin that brought blockchain to public attention, but the two are not synonymous. Blockchain is the underlying technology for Bitcoin, enabling bitcoin transactions to occur directly between two parties without going through a third party like a bank.
Myth: Blockchain is fintech
Blockchain is often thought as being a financial services technology, because of its association with cryptocurrencies like Bitcoin as well as the high level of interest shown by the fintech sector. However, its application for the purpose of tracking and recording data can add value to many sectors—such as agriculture, healthcare, real estate and retail, to name just a few.
Myth: There is only one type of blockchain
There is more than just one type of blockchain. In a public blockchain, anyone can read and write the blockchain and participate in the consensus process. In a private blockchain, a central authority regulates everything in the blockchain, including writing and reading from the chain and the consensus process—hence, it is not free for anyone and everyone. In a permissioned (private) blockchain, a predefined set of members have a role in the consensus mechanism and have special rights to read and/or write to the blockchain.