Ethereum is an open-source blockchain platform that allows anyone to build and use decentralized applications running on blockchain technology. Ethereum is a programmable blockchain - it allows users to create their own operations. These operations, coded as Smart Contracts, are deployed and executed by the Ethereum Virtual Machine (EVM) running inside every node.
Private blockchains, or as I like to call them, shared databases, have a place in improving efficiency for financial institution for back-office settlement processes. They should not be seen as controversial, or part of some dialectic struggle between punks and police. To the extent that the identifying shroud of AML/KYC can be placed into public blockchain metadata (possible in Omni Layer transactions over the Bitcoin blockchain) there may even be interoperability between these two sides of the train tracks. Right now, due to state-granted monopolies to issue credit, most of the world's liquidity is still in banks. However, we believe that in the long-term, public blockchains, especially those based on work, will come to take a more significant part in the ‘System D’ informal economy, which is where most of the global economic growth will originate.” 
Every node in a decentralized system has a copy of the blockchain. Data quality is maintained by massive database replication[8] and computational trust. No centralized "official" copy exists and no user is "trusted" more than any other.[4] Transactions are broadcast to the network using software. Messages are delivered on a best-effort basis. Mining nodes validate transactions,[22] add them to the block they are building, and then broadcast the completed block to other nodes.[24]:ch. 08 Blockchains use various time-stamping schemes, such as proof-of-work, to serialize changes.[34] Alternative consensus methods include proof-of-stake.[22] Growth of a decentralized blockchain is accompanied by the risk of centralization because the computer resources required to process larger amounts of data become more expensive.[35]
"Proof of Work" used by Bitcoin is a competitive consensus algorithm. Each node races to solve a difficult puzzle first. Doing so earns the right to produce a block and you are rewarded in Bitcoin. The block is where the transaction (value of data) is written and confirmed. However, this race is a waste of time and money for those that don’t win. You get nothing unless you are the first to solve the puzzle. Since no one wants to lose, nodes started working together to solve the puzzle and share the reward based on your computational power (the hash rate).
Nikolai Hampton pointed out in Computerworld that "There is also no need for a '51 percent' attack on a private blockchain, as the private blockchain (most likely) already controls 100 percent of all block creation resources. If you could attack or damage the blockchain creation tools on a private corporate server, you could effectively control 100 percent of their network and alter transactions however you wished."[9] This has a set of particularly profound adverse implications during a financial crisis or debt crisis like the financial crisis of 2007–08, where politically powerful actors may make decisions that favor some groups at the expense of others,[51][52] and "the bitcoin blockchain is protected by the massive group mining effort. It's unlikely that any private blockchain will try to protect records using gigawatts of computing power—it's time consuming and expensive."[9] He also said, "Within a private blockchain there is also no 'race'; there's no incentive to use more power or discover blocks faster than competitors. This means that many in-house blockchain solutions will be nothing more than cumbersome databases."[9]
Put simply, sidechaining is any mechanism that allows tokens from one blockchain to be securely used within a completely separate blockchain but still moved back to the original chain if necessary. By convention the original chain is normally referred to as the "main chain", while any additional blockchains which allow users to transact within them in the tokens of the main chain are referred to as "sidechains". For example, a private Ethereum-based network that had a linkage allowing ether to be securely moved from the public Ethereum main chain onto it and back would be considered to be a sidechain of the public network.
A public blockchain is ideal when the network must be truly decentralized, which means that no central entity controls the entry of the members on the network and the consensus mechanism is democratic. A democratic mechanism of consensus means that all members can become a minor and that these miners are in competition to add the blocks to the blockchain (at least when the mechanism of the evidence of the work is used).
Sidechains allow cryptocurrencies to interact with one another. They add flexibility and allow developers to experiment with Beta releases of Altcoins or software updates before pushing them on to the main chain. Traditional banking functions like issuing and tracking ownership of shares can be tested on sidechains before moving them onto main chains. If the security mechanisms for sidechains can be bolstered, sidechain technology holds promise for massive blockchain scalability.
Public blockchains provide a way to protect the users of an application from the developers, establishing that there are certain things that even the developers of an application have no authority to do. From a naive standpoint, it may be hard to understand why an application developer would want to voluntarily give up power and hamstring themselves. However, more advanced economic analysis provides two reasons why, in Thomas Schelling's words, weakness can be a strength. First, if you explicitly make it harder or impossible for yourself to do certain things, then others will be more likely to trust you and engage in interactions with you, as they are confident that those things are less likely to happen to them. Second, if you personally are being coerced or pressured by another entity, then saying "I have no power to do this even if I wanted to" is an important bargaining chip, as it discourages that entity from trying to compel you to do it. A major category of pressure or coercion that application developers are at risk of is that by governments, so "censorship resistance" ties strongly into this kind of argument.
But, rather than go back to the drawing board, many people are figuring out alternative way to eke better performance outbid the system, and one approach is to use a sidechain.. sonrsther than process many transactions on the bitcoin network, two parties that transact a lot together might deposit down bitcoin into a side chain and conduct a bunch of transactions there (avoiding the absurd cost and delay of bitcoin) and then when they want to “settle up” they then invoke a balancing transaction on the bitcoin network.
The original Litecoin we started out with are now Rootstock Litecoin, which I can use for creating smart contracts and as previously mentioned Sidechains can exist for all types of digital assets with propositions of not only smart contracts but the ability to provide more freedom for experimentation with Beta releases of core software and Altcoins, as well as the taking over of traditional banking instruments such as the issuing and tracking of shares, bonds and other assets.
– A consensus much faster: the fact that the consensus mechanism is centralized makes it much quicker. In fact, the term “consensus” is no longer adapted since it is rather a recording of transactions on the blockchain. Note that the entity responsible for managing the blockchain can decide to change the parameters of the blockchain and in particular to increase the size of the blocks to be able to add more transactions.
Jump up ^ Epstein, Jim (6 May 2016). "Is Blockchain Technology a Trojan Horse Behind Wall Street's Walled Garden?". Reason. Archived from the original on 8 July 2016. Retrieved 29 June 2016. mainstream misgivings about working with a system that's open for anyone to use. Many banks are partnering with companies building so-called private blockchains that mimic some aspects of Bitcoin's architecture except they're designed to be closed off and accessible only to chosen parties. ... [but some believe] that open and permission-less blockchains will ultimately prevail even in the banking sector simply because they're more efficient.
Unfortunately our second option cannot be done yet, because to use these sidechains, main chain (here it is bitcoin) needs to do some upgrade (soft fork). By the way, upgrades in public blockchains are very painful yet. There will be a user activated soft fork (UASF) on August 1. All bitcoin forms’ trend topic is this soft fork which is about a code change for Segregated Witness Adoption.
A public blockchain is a platform where anyone on the platform would be able to read or write to the platform, provided they are able to show the proof of work for the same. There has been a lot of activity in this space as the number of potential users that any technology in this space could generate is high.  Also, a public blockchain is considered to be a fully decentralized blockchain. Some of the examples are:
– A consensus much faster: the fact that the consensus mechanism is centralized makes it much quicker. In fact, the term “consensus” is no longer adapted since it is rather a recording of transactions on the blockchain. Note that the entity responsible for managing the blockchain can decide to change the parameters of the blockchain and in particular to increase the size of the blocks to be able to add more transactions.
This is justified by observing that, in our pre-sidechain world, miners always want things to be correct. In theory, the incentives of miners and investors are very strongly aligned: both are compensated most when the exchange rate is highest. And, in practice, we do not see large reorganizations (where miners can “steal”, by first depositing BTC to major exchanges, then selling that BTC for fiat (which they withdraw), and finally rewriting the last 3 or 4 days of chain history, to un-confirm the original deposits). These reorgs would devastate the exchange rate, as they would cast doubt on the entire Bitcoin experiment. The thesis of Drivechain is that sidechain-theft would also devastate the exchange rate, as it would cast doubt on the entire sidechain experiment (which would itself cast doubt on the Bitcoin experiment, given the anti-competitive power of sidechains).
The main point of a side-chain is to allow cryptocurrency networks to scale and interact with one-another. For example alt-coins and Bitcoin run on separate chains, however side chains allow for these separate currencies to be transferred through these two-way 'portal's or interfaces via a fixed conversion amount. Added benefits of side-chains are different asset classes like,stocks, bonds etc being integrated through a converted price onto the main chain, along with additional functionality like smart contracts,unique D-Apps, micro-payments and security updates that can be later incorporated into the primary network from these side-chains.
Hasta la fecha (Agosto del 2016), las sidechains sobre Bitcoin no son más que algo teórico. Una implementación de este tipo requeriría de un cambio en el código Bitcoin (hay miembros de la comunidad Bitcoin con gran prestigio, como es el caso de Peter Todd, que argumentan que una sidechain, tal y como la describe Blockstream en su paper, no podrían llevarse a la práctica en Bitcoin sin hacer un gran cambio, hard fork, en Bitcoin). En el mismo paper de blockstream se reconoce que una implementación de este tipo, la cual su teoría es simple pero su implementación compleja, se enfrenta a problemas que no está del todo claro que puedan solventarse (y no todos son de tipo técnico).
Blockchain, trust, decentralization, Bitcoin, transparency, anonymity, blockchain, blockchain, blockchain. These words seem to appear randomly on the Web regardless the theme of an article you read. Don’t you know how to implement blockchain in art? There’s definitely someone who can tell you. Do you wonder how banking can benefit from blockchain? No worries, some projects already do it – just search for the use cases.
Jump up ^ Shah, Rakesh (1 March 2018). "How Can The Banking Sector Leverage Blockchain Technology?". PostBox Communications. PostBox Communications Blog. Archived from the original on 17 March 2018. Banks preferably have a notable interest in utilizing Blockchain Technology because it is a great source to avoid fraudulent transactions. Blockchain is considered hassle free, because of the extra level of security it offers.
Imagine over several hours, the camps produced a chain of messages that each required intensive Proof of Work. This means that the majority of the camps had to agree on this chain of messages and each camp can confidently trust the final outcome. It’s important to note here that Proof of Work does not care about the message itself, only that the nodes agreed to the final message. This majority network consensus keeps it secure and provides a solution to the Byzantine Generals Problem, leading to Byzantine Fault Tolerance.
In general, so far there has been little emphasis on the distinction between consortium blockchains and fully private blockchains, although it is important: the former provides a hybrid between the “low-trust” provided by public blockchains and the “single highly-trusted entity” model of private blockchains, whereas the latter can be more accurately described as a traditional centralized system with a degree of cryptographic auditability attached. However, to some degree there is good reason for the focus on consortium over private: the fundamental value of blockchains in a fully private context, aside from the replicated state machine functionality, is cryptographic authentication, and there is no reason to believe that the optimal format of such authentication provision should consist of a series of hash-linked data packets containing Merkle tree roots; generalized zero knowledge proof technology provides a much broader array of exciting possibilities about the kinds of cryptographic assurances that applications can provide their users. In general, I would even argue that generalized zero-knowledge-proofs are, in the corporate financial world, greatly underhyped compared to private blockchains.
Sidechains with specific purposes could be formed with specific features while still enjoying the widespread adoption and value that Bitcoin holds.  Most importantly it can add these features without consensus from the Bitcoin community. Sidechains have the potential to replace many Cryptocurrencies as it allows features that were previously unique to these currencies to be available on Bitcoin. It also allows developers to experiment with sidechains and scope its full potential while still keeping coins linked to Bitcoin.
By definition, blockchain is a ledger of all transactions that have been executed and could be seen as a write-only platform, wherein transactions once executed cannot be modified later. This platform has been further divided into Public and Private blockchain. Is there a third one? a hybrid mode such as a ‘Consortium blockchain’ as represented by Vitalik Buterin, founder of Ethereum, a decentralized web 3.0 publishing platform.
Saying that, Interoperability has been the missing link in conquering the obstacles faced by both private and public blockchains by empowering them to interact and exchange values across platforms seamlessly. Developers use of the Gallactic blockchain technology, that allow for private and public blockchains within its eco-system, will drive the potential to combine both public and private blockchains with innovative new solutions, designed to accomplish cross-chain exchange and greater compatibility is the way forward for all parties and their concerns.
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