Plasma is a proposed framework for incentivized and enforced execution of smart contracts which is scalable to a significant amount of state updates per second (potentially billions) enabling the blockchain to be able to represent a significant amount of decentralized financial applications worldwide. These smart contracts are incentivized to continue operation autonomously via network transaction fees, which is ultimately reliant upon the underlying blockchain (e.g. Ethereum) to enforce transactional state transitions.
The great thing about Bitcoin, for a tech columnist like me, is that it’s simultaneously over-the-top cinematic and technically dense. Richard Branson recently hosted a “Blockchain Summit” at his private Caribbean island. There’s a Bitcoin Jet. At the same time, 2015 has seen the release of a whole slew of technically gnarly–and technically fascinating–proposals built atop the Bitcoin blockchain.
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.
Lisk es una plataforma open source en la que se pueden desarrollar y ejecutar smart contracts en forma de aplicaciones descentralizadas o DAPPS multiplataforma. Éstas, y como uno de los puntos fuertes de Lisk, son desarrolladas con, posiblemente, el lenguaje de programación más famoso y usado, Javascript. Aunque con un enfoque genérico, ya han empezado a aparecer algunas soluciones e interés en sectores concretos, como es el caso del Internet de las cosas que, junto a Chain of Things, están empezando a explotar.
A federation is a group that serves as the intermediary between a parent chain and its corresponding sidechain. It is an additional layer in the protocol but serves a key function and is what Blockstream’s Liquid sidechain uses. Due to the lack of expressiveness of Bitcoin’s scripting language, an externally implemented and mutually distrusting set of members form a federated peg.
“Such brazen theft would indicate [1] that Bitcoin would be (in the near future) without sidechains of any kind, and [2] that Bitcoin itself may be in danger from the miners (and we may need to consider using an alternate proof-of-work hash function),” he explained the impact of this setup in his original post on the topic. Like SPV sidechains, drivechains require a soft-forking change to Bitcoin.
It is different with a private blockchain (or closed) since the members of the network are selected before being able to download the protocol and therefore use the proposed service by the network. The mining capabilities and the system of consensus as a whole are centralized within the hands of the same entity. A network based on a private blockchain is therefore not decentralized in itself.

In September 2015, the first peer-reviewed academic journal dedicated to cryptocurrency and blockchain technology research, Ledger, was announced. The inaugural issue was published in December 2016.[91] The journal covers aspects of mathematics, computer science, engineering, law, economics and philosophy that relate to cryptocurrencies such as bitcoin.[92][93]

A consortium blockchain is part public, part private. This split works at the level of the consensus process: on a consortium chain, a pre-selected group of nodes control the consensus process, but other nodes may be allowed to participate in creating new transactions and/or reviewing it. The specific configuration of each consortium chain (i.e., which nodes have the power to authorize transactions via the consensus process, which can review the history of the chain, which can create new transactions, and more) is the decision of each individual consortium.
What if we could run heavy computations in a more centralized fashion, say on a single server, and then periodically integrate the results onto the main blockchain for posterity. We temporarily expose some vulnerability while the parallel server runs the heavy computation, but we get a massive benefit in that we don’t have to run the computation on chain, and simply need to store the results for future verification. This is the general premise behind Truebit. We won’t get into all the details of Truebit but there is a concept of challengers, who check to see the computations that were made have high fidelity.
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]

A federation is a group of servers that act as an in-between point between the main chain and a sidechain. The Federation decides when the user’s coins are locked as well as when they are released. The developers of the sidechains can choose the members of the federation. The downside to using federations is that they add another layer between the sidechains and the parent chain.

A user on the parent chain first has to send their coins to an output address, where the coins become locked so the user is unable to spend them elsewhere. Once the transaction has been completed, a confirmation is communicated across the chains followed by a waiting period for extra security. After the waiting period, the equivalent number of coins is released on the sidechain, allowing the user to access and spend them there. The reverse happens when moving back from a sidechain to the main chain.

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 have been a concept for a relatively long time in the cryptocurrency space. The idea took flight in 2014 when several eminent figures in cryptography and early digital currency innovations published an academic paper introducing Pegged Sidechains. Several of the authors are central figures at Blockstream, who is at the forefront of innovation in sidechains and other Bitcoin developments.
Counterfeiting items is a $1.2 trillion global problem, according to Research and Markets 2018 Global Brand Counterfeiting Report. The rise of online commerce and third-party marketplace sellers have made the crime more prevalent in recent years. Blockchain technology can help consumers verify what they ordered online and what they receive in the mail is what they intended to purchase.
To most people, Bitcoin itself is already deeply esoteric (and many still find it risible.) But to cryptocurrency aficionados, tired old garden-variety Bitcoin is so five minutes ago. Explaining today’s new cryptocurrency hotness to a general audience is an interesting challenge–I have an engineering degree from a top-tier school and I write software for a living, and I still find much of this material pretty impenetrable on first acquaintance–but here goes:
And now for the second clever part. The logic above is symmetric. So, at any point, whoever is holding these coins on the sidechain can send them back to the Bitcoin network by creating a special transaction on the sidechain that immobilises the bitcoins on the sidechain. They’ll disappear from the sidechain and become available again on the Bitcoin network, under the control of whoever last owned them on the sidechain.
Ethereum, a provider of decentralized platform and programming language that helps running smart contracts and allows developers to publish distributed applications. Factom, a provider of records management, record business process for business and governments. Blockstream, a provider of sidechain technology, focused on extending capabilities of Bitcoin. The company has started experimenting on providing accounting (considered a function to be done on private blockchain) with the use of public blockchain technology.
As you know, we at LTP have been doing a lot of research to understand other use cases of blockchain apart from Bitcoin-based payments. Recently we had released a comprehensive analysis of 50+ startups and 20 use-cases of blockchain. Though there have been news of large companies accepting bitcoin (Ex.: Amazon, Microsoft, Dell) and the overall acceptance reaching a 100,000+ merchants figure, upon deeper examination we realize that large corporations do not store the Bitcoin payments. They generally partner with a Bitcoin payment processor who converts the Bitcoins to cash as and when they receive a payment and this converted amount is what the corporates take into their account. What a bummer!
Function	Transactions executed between the locks and unlocks of the main chain tokens don't bloat the main chain. As the technology of a side chain is connected to its main chain, it can be used to build on the developments of the main chain and introduce new features to the market.	Child chains serve as the transactional chains of the parent-child architecture, as the parent chain retains minimal features.

Consider a proof-of-existence application, where you want to authenticate your document in the Ethereum (for example) network, but you do not need your document to be online. So, you will store the hash generated from your document in the blockchain, but the document itself will be in your local machine, out of any blockchain-related structured, being off-chain.
Tú, o el usuario en cuestión de las sidechains, envía los bitcoins a una dirección Bitcoin específica, sabiendo que, una vez mandados, estarán fuera de tu control y fuera del control de cualquier otra persona. Estarán completamente inmovilizados y sólo se podrán desbloquear si alguien puede demostrar que no se están utilizando en ningún otro lugar.
The top 10 Ethereum decentralized apps (DApps) have daily active user counts in the thousands. Compare this with a centralized platform like Facebook, which has over a billion daily users, and you can see just how small scale blockchain use still remains. For a detailed comparison, read “State of the DApps: 5 Observations From Usage Data (April 2018)”.
This type of permissioned blockchain model offers the ability to leverage more than 30 years of technical literature to realize significant benefits. Digital identity in particular, is fundamental for most industry use cases, be it handling supply chain challenges, disrupting the financial industry, or facilitating security-rich patient/provider data exchanges in healthcare. Only the entities participating in a particular transaction will have knowledge and access to it — other entities will have no access to it. Permissioned blockchains also permit a couple of orders of magnitude greater scalability in terms of transactional throughput.