If one group of nodes continues to use the old software while the other nodes use the new software, a split can occur. For example, Ethereum has hard-forked to "make whole" the investors in The DAO, which had been hacked by exploiting a vulnerability in its code.[31] In this case, the fork resulted in a split creating Ethereum and Ethereum Classic chains. In 2014 the Nxt community was asked to consider a hard fork that would have led to a rollback of the blockchain records to mitigate the effects of a theft of 50 million NXT from a major cryptocurrency exchange. The hard fork proposal was rejected, and some of the funds were recovered after negotiations and ransom payment.[32]
“Given all of this, it may seem like private blockchains are unquestionably a better choice for institutions. However, even in an institutional context, public blockchains still have a lot of value, and, in fact, this value lies to a substantial degree in the philosophical virtues that advocates of public blockchains have been promoting all along, among the chief of which are freedom, neutrality and openness.” 
Walmart recently filed patents that could allow the retailer to store vendor and consumer e-commerce payment data using blockchain technology to improve security. This application would encrypt payment information in digital shopping systems and create a network able to automatically conduct transactions on behalf of a customer. The payments would be received by one vendor or more, depending on the services and who provided them.
Let’s switch gears quickly before we get back to talking about trust mechanisms. We’ll define what a “smart contract” is. The first blockchain that was popularized is obviously the Bitcoin blockchain. But the functionality of Bitcoin is very limited. All it can do is record transaction information. It’s only useful to keep track of the fact that Alice sent Bob 1 Bitcoin.
The paper outlines some critical developments and associated problems that were both currently trending and forward-thinking at the time, many of them still very much relevant today. At the time, altcoins were quickly gaining prominence and the problems associated with their volatility, security, and lack of interoperability with Bitcoin raised concerns. The paper primarily addressed 6 issues that pegged sidechains aimed to provide a solution:
“The reason why you put up private blockchains is potentially because you want to have control over the participants in the blockchain. So as we have banks and financial institutions, who have to worry heavily about regulations, they can’t use the public blockchains right now because they are open and permission-free, and anyone can participate, and that’s contradictory to the regulations to which they must abide.
A typical use case for a private blockchain is intra-business: when a company decides to implement blockchain as a business solution, they may opt for a chain to which only company members have access. This is useful if there’s no need for anybody outside of the company to become part of the chain, because private blockchains are more efficient than public and consortium chains. Also, because they are smaller and contained, it is easier for a consensus process or other technical stipulation to be altered on a blockchain. So, for example, if the developers or proprietors want to change the cryptographic method which runs its consensus process, it is much easier to do this on a private blockchain than a public or consortium chain.
Structure Side chains are independent blockchains that have a kind of "pegging mechanism", where at least one of the chains (main chain and side chain) is "aware" of the other chain and both tokens are pegged at a set ratio. Side chains need their own network security and block processing. "Child Chains" of the Ardor platform are tightly integrated into the main Ardor parent chain. All transactions are processed and secured by the parent chain forgers. This makes cross-chain transactions possible. Pruning will be enabled on child chain transactions in order to significantly reduce blockchain bloat by pruning the transactions on regular basis from the blockchain.
The NPD report noted IBM is partnering with nine retailers and food companies (Walmart, Unilever, Nestle, Dole, Tyson Foods, Golden State Foods, McCormick & Co., McLane Co., and Driscoll’s) to revamp data management processes with blockchain. Walmart uses blockchain in China to source its pork all the way from the pig to the customer. This enables the retailers to provide transparency to all the players along the supply chain.
“Amit Goel is the Founder & Chief Strategy & Innovation Officer for MEDICI. Amit’s vision is to build a strong FinTech market network that involves financial institutions, banks, startups, investors, analysts & other key stakeholders across the ecosystem – helping each one of them in a meaningful way by removing the asymmetry of information and providing a platform to engage & transact.\ \ Amit is passionate about bringing actionable FinTech-focused insights, innovative products & services for the FinTech ecosystem. Some of his work involves startup scores, bank scores/assessments, predictive viewpoints & other innovations that have helped MEDICI’s customers and the ecosystem. He has been named amongst the Top 100 FinTech thought leaders/influencers in the world & Top 10 in Asia multiple times by reputed agencies, consulting firms as well as financial institutions. Amit has built MEDICI (formerly LTP) as a new-age, tech-enabled advisory/research firm, which is now considered the #1 global research & innovation platform for FinTech in the world.\ \ Amit has been writing pioneering viewpoints on financial technology space that have been ahead of the curve since 2010. His data-driven predictions have helped the customers as well as the ecosystem. His past work experience includes a strong background in strategy & market analysis and advisory to clients (from big business houses to Fortune 500 firms) in payments, commerce, financial services & IT/technology. In the past, Amit had also founded a successful consulting & research practice called GrowthPraxis and has worked at Boston Analytics, Frost & Sullivan, and Daimler Chrysler in strategy & research.”
There has been tremendous interest in blockchain, the technology on which Bitcoin functions. Nakamoto developed the blockchain as an acceptable solution to the game theory puzzle – Byzantine General’s Problem. This lead to a number of firms adopting the technology in different ways to solve real world issues, wherever there was an element of trust involved. Majority of them could be relating to the ability to provide proof of ownership – for documents, software modules/licenses, voting etc.
In simple terms, public blockchains can receive and send transactions from anybody in the world. They can also be audited by anybody, and every node has as much transmission power as any other. Before a transaction is considered valid, it must be authorized by each of its constituent nodes via the chain’s consensus process. As long as each node abides by the specific stipulations of the protocol, their transactions can be validated, and thus add to the chain
That is however not all. Sidechains also have some specific use cases, unique to a certain blockchain. One example is the usage of sidechains in EOS. EOS is currently facing a RAM problem. RAM is too expensive and developers are complaining. Sidechains could compete with the EOS mainchain by having lower RAM prices, this would lead to competition, incentivizing both the EOS mainchain block producers and sidechain block producers (mainchain and sidechains of EOS are maintained by the same group of block producers) to keep the RAM price as low as possible. This also means there is more RAM available, so the RAM price will go down as a result.
A diferencia con la, hasta ahora, plataforma estrella de smart contracts Ethereum, otra de las diferencias más importantes de Lisk es que, en Lisk, cada aplicación corre sobre su propia sidechain y no sobre una única cadena, cómo es el caso de Ethereum. Por lo tanto, un entorno propio e independiente que podrá exprimir cada desarrollador para cada DAPP desarrollada con un backend en JS/NodeJS y un frontend HTML/CSS/JS.
Let's explore if there is a hybrid blockchain concept (third type). A consortium blockchain would be a mix of both the public and private. Wherein the ability to read & write could be extended to a certain number of people/nodes. This could be used by groups of organization/firms, who get together, work on developing different models by collaborating with each other. Hence, they could gain a blockchain with restricted access, work on their solutions and maintain the intellectual property rights within the consortium.
“Private blockchains are valuable to solve efficiency, security and fraud problems within traditional financial institutions, but only incrementally. Private blockchains will not revolutionize the financial system. Public blockchains, however, hold the potential to replace most functions of traditional financial institutions with software, fundamentally reshaping the way the financial system works.” 
This approach isn’t fool-proof, but it’s not by mistake that the system looks the way it does today (that’s my history degree talking). Despite best technical efforts, human problems remain within the realm of probability. From http://www.nytimes.com/2009/01/15/books/15masl.html: “…blame cannot be easily assigned: not even the most sophisticated economists of the era could accurately predict disaster, let alone guard against it. The effects of a public herd mentality at the time of the [insert catastrophe here] are depicted, all too recognizably, as unstoppable.”
^ Jump up to: a b c d e f g h i j k l "Blockchains: The great chain of being sure about things". The Economist. 31 October 2015. Archived from the original on 3 July 2016. Retrieved 18 June 2016. The technology behind bitcoin lets people who do not know or trust each other build a dependable ledger. This has implications far beyond the crypto currency.

“Private blockchains are valuable to solve efficiency, security and fraud problems within traditional financial institutions, but only incrementally. Private blockchains will not revolutionize the financial system. Public blockchains, however, hold the potential to replace most functions of traditional financial institutions with software, fundamentally reshaping the way the financial system works.”