– The manipulation of the blockchain: It is indeed possible to come back at any time on the transactions that have already been added to the blockchain and therefore change the balance of the members. In a public blockchain, such operation would require that 51% of the hashing power (i.e capacity to mine) is concentrated in the hands of the same entity. This not theory anymore since it happened beginning 2014 when the cooperative of GHash minor reached the 51% threshold.

By the end of this post, you’ll be able to freely participate in conversations like the above. This is not a coding tutorial, as we’ll just be presenting important concepts at a high level. However, we may follow up with programming tutorials on these ideas. This article will be helpful to both programmers and non-programmers alike. Let’s get going!
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.
We use node 2 to receive a payment of 200 via the smart contract function, receivePayment(). Note that the receivePayment() function can accept a second parameter for the account address that is used to create this transaction. (Note that you can also set web3.eth.defaultAccount = "<…account address…>", after which you can just call receivePayment(200) with one parameter.)
State of the art public Blockchain protocols based on Proof of Work (PoW) consensus algorithms are open source and not permissioned. Anyone can participate, without permission. (1) Anyone can download the code and start running a public node on their local device, validating transactions in the network, thus participating in the consensus process – the process for determining what blocks get added to the chain and what the current state is. (2) Anyone in the world can send transactions through the network and expect to see them included in the blockchain if they are valid. (3) Anyone can read transaction on the public block explorer. Transactions are transparent, but anonymous/pseudonumous.
Incorporated in 2009 and headquartered in the USA, Techtic Solutions Inc. is an leading web and mobile app development company known for delivering innovative solutions for any complex problem. Our mission remains the same; “PRODUCE UNPARALLELED TECH ENABLED SOLUTIONS BENCHMARKING LATEST TECHNOLOGY STANDARDS” Facts & Figures: A service provider in over 30 countries with offices in: USA & India 250+ mobile applicatio ... Read more
It may sound nitpicky, but I think that description leaves something to be desired in terms of presenting the “correct” mental model. First, there is no such thing as “a” bitcoin, as I am sure the author would agree. Speaking of spending or moving bitcoins perpetuates the notion of bitcoins as “things”. It might be preferable to say that you are spending or moving “units of the bitcoin protocol”. There is something similar going on here with dollars. The dollars in your bank account aren’t things either, they are units of demand or claim on a currency. The fact that printed dollars have serial numbers tends to confuse this notion. Treating something as a “thing’ which is not a thing is sometimes referred to as the reification fallacy.
A blockchain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the consensus of the network.[1][18] This allows the participants to verify and audit transactions inexpensively.[19] A blockchain database is managed autonomously using a peer-to-peer network and a distributed timestamping server. They are authenticated by mass collaboration powered by collective self-interests.[20] The result is a robust workflow where participants' uncertainty regarding data security is marginal. The use of a blockchain removes the characteristic of infinite reproducibility from a digital asset. It confirms that each unit of value was transferred only once, solving the long-standing problem of double spending. Blockchains have been described as a value-exchange protocol.[13] This blockchain-based exchange of value can be completed quicker, safer and cheaper than with traditional systems.[21] A blockchain can assign title rights because, when properly set up to detail the exchange agreement, it provides a record that compels offer and acceptance.
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.
Another technology that could see more widespread use in the coming years is side chains. A side chain is defined for one specific use case. There can be multiple side chains where different tasks are distributed accordingly for improving the efficiency of processing. Maybe one application needs to optimize for high speeds and another needs to optimize for large computations. In any case, side chains can be used to handle commercial blockchain usage. CryptoKitties would have greatly benefitted from an optimized high-speed side chain. At one point, they jammed up the Ethereum blockchain with 25% of all transactions coming from their application.

LeewayHertz provides end to end solution to build enterprise-grade blockchain applications.  Experienced in developing multiple blockchain applications for Global Supply Chain, Identity Solution on blockchain and utility bill generation using blockchain.  LeewayHertz has experience working with distributed ledger technology including Hyperledger, Ethereum, R3Corda, and Hashgraph. The team also includes Hedera Hashgraph ambassadors ... Read more

The first work on a cryptographically secured chain of blocks was described in 1991 by Stuart Haber and W. Scott Stornetta.[10][6] They wanted to implement a system where documents' timestamps could not be tampered with or backdated. In 1992, Bayer, Haber and Stornetta incorporated Merkle trees to the design, which improved its efficiency by allowing several documents to be collected into one block.[6][11]

Blockchain-based smart contracts are proposed contracts that could be partially or fully executed or enforced without human interaction.[55] One of the main objectives of a smart contract is automated escrow. An IMF staff discussion reported that smart contracts based on blockchain technology might reduce moral hazards and optimize the use of contracts in general. But "no viable smart contract systems have yet emerged." Due to the lack of widespread use their legal status is unclear.[56]
The consortium or company running a private blockchain can easily, if desired, change the rules of a blockchain, revert transactions, modify balances, etc. In some cases, eg. national land registries, this functionality is necessary; there is no way a system would be allowed to exist where Dread Pirate Roberts can have legal ownership rights over a plainly visible piece of land, and so an attempt to create a government-uncontrollable land registry would in practice quickly devolve into one that is not recognized by the government itself. Of course, one can argue that one can do this on a public blockchain by giving the government a backdoor key to a contract; the counter-argument to that is that such an approach is essentially a Rube Goldbergian alternative to the more efficient route of having a private blockchain, although there is in turn a partial counter-argument to that that I will describe later.

Quest Global Technologies is a leading software development organization that works on Blockchain, customized ERP, Mobile Apps, Salesforce and Web Development. Quest Global Technologies has been rated as TOP mobile application developers by Appfutura and is covered by Entrepreneur Magazine. Quest Global Technologies has the vision to make its clients successful by leveraging technology to increase sales, automation and reduce wastage. www.cryp ... Read more
Similarly, a side chain is a separate blockchain that runs in parallel to the main chain. The term is usually used in relation to another currency that’s pegged to the currency of the main chain. For example, staying with the Starcraft motif, say we had an in-game currency called Minerals (oh wait, we do!). We could allow players to peg their Ether (or ETH) to purchase more Minerals in-game. So we reserve some ETH on the main chain, and peg, say 500 Minerals to 1 ETH.

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.

By the end of this post, you’ll be able to freely participate in conversations like the above. This is not a coding tutorial, as we’ll just be presenting important concepts at a high level. However, we may follow up with programming tutorials on these ideas. This article will be helpful to both programmers and non-programmers alike. Let’s get going!
The ShipChain platform unifies shipment tracking on the Ethereum blockchain, using a sidechain to track individual encrypted geographic waypoints across each smart contract. With this system, the meaning of each cryptographic waypoint is only accessible for interpretation by the parties involved in the shipment itself. This gives shippers more visibility across their supply chain, and allows carriers to communicate with ease. 

@tradles – thanks for taking the time to explain this. OK – so I get the debate around blockchain bloat and the (grudging) inclusion of OP_RETURN, etc., but what I’m missing is that I can only really see one scenario where embedding any identity data into the blockchain makes sense…. and that’s when I want to *associate* an identity with a transaction I’m performing.
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:
Looking for a top private blockchain open source? Here is a list of private blockchain development companies with client reviews and ratings. Private blockchain network on contrary to public and permission blockchain can be run and utilized by one organization only. Additionally, private blockchain platform organizes distinctive components of the technology in order to serve different applications. By prioritizing productivity over the secrecy, permanence, and transparency, private blockchain open source adheres to the qualities normally connected with the technology. The scope of uses for private blockchain might be narrow yet its power to enhance processes are no less important. GoodFirms has thus created a list of top private blockchain companies below:
!function(n,t){function r(e,n){return Object.prototype.hasOwnProperty.call(e,n)}function i(e){return void 0===e}if(n){var o={},s=n.TraceKit,a=[].slice,l="?";o.noConflict=function(){return n.TraceKit=s,o},o.wrap=function(e){function n(){try{return e.apply(this,arguments)}catch(e){throw o.report(e),e}}return n},o.report=function(){function e(e){l(),h.push(e)}function t(e){for(var n=h.length-1;n>=0;--n)h[n]===e&&h.splice(n,1)}function i(e,n){var t=null;if(!n||o.collectWindowErrors){for(var i in h)if(r(h,i))try{h[i].apply(null,[e].concat(a.call(arguments,2)))}catch(e){t=e}if(t)throw t}}function s(e,n,t,r,s){var a=null;if(w)o.computeStackTrace.augmentStackTraceWithInitialElement(w,n,t,e),u();else if(s)a=o.computeStackTrace(s),i(a,!0);else{var l={url:n,line:t,column:r};l.func=o.computeStackTrace.guessFunctionName(l.url,l.line),l.context=o.computeStackTrace.gatherContext(l.url,l.line),a={mode:"onerror",message:e,stack:[l]},i(a,!0)}return!!f&&f.apply(this,arguments)}function l(){!0!==d&&(f=n.onerror,n.onerror=s,d=!0)}function u(){var e=w,n=p;p=null,w=null,m=null,i.apply(null,[e,!1].concat(n))}function c(e){if(w){if(m===e)return;u()}var t=o.computeStackTrace(e);throw w=t,m=e,p=a.call(arguments,1),n.setTimeout(function(){m===e&&u()},t.incomplete?2e3:0),e}var f,d,h=[],p=null,m=null,w=null;return c.subscribe=e,c.unsubscribe=t,c}(),o.computeStackTrace=function(){function e(e){if(!o.remoteFetching)return"";try{var t=function(){try{return new n.XMLHttpRequest}catch(e){return new n.ActiveXObject("Microsoft.XMLHTTP")}},r=t();return r.open("GET",e,!1),r.send(""),r.responseText}catch(e){return""}}function t(t){if("string"!=typeof t)return[];if(!r(j,t)){var i="",o="";try{o=n.document.domain}catch(e){}var s=/(.*)\:\/\/([^:\/]+)([:\d]*)\/{0,1}([\s\S]*)/.exec(t);s&&s[2]===o&&(i=e(t)),j[t]=i?i.split("\n"):[]}return j[t]}function s(e,n){var r,o=/function ([^(]*)\(([^)]*)\)/,s=/['"]?([0-9A-Za-z$_]+)['"]?\s*[:=]\s*(function|eval|new Function)/,a="",u=10,c=t(e);if(!c.length)return l;for(var f=0;f0?s:null}function u(e){return e.replace(/[\-\[\]{}()*+?.,\\\^$|#]/g,"\\$&")}function c(e){return u(e).replace("<","(?:<|<)").replace(">","(?:>|>)").replace("&","(?:&|&)").replace('"','(?:"|")').replace(/\s+/g,"\\s+")}function f(e,n){for(var r,i,o=0,s=n.length;or&&(i=s.exec(o[r]))?i.index:null}function h(e){if(!i(n&&n.document)){for(var t,r,o,s,a=[n.location.href],l=n.document.getElementsByTagName("script"),d=""+e,h=/^function(?:\s+([\w$]+))?\s*\(([\w\s,]*)\)\s*\{\s*(\S[\s\S]*\S)\s*\}\s*$/,p=/^function on([\w$]+)\s*\(event\)\s*\{\s*(\S[\s\S]*\S)\s*\}\s*$/,m=0;m]+)>|([^\)]+))\((.*)\))? in (.*):\s*$/i,o=n.split("\n"),l=[],u=0;u=0&&(g.line=v+x.substring(0,j).split("\n").length)}}}else if(o=d.exec(i[y])){var _=n.location.href.replace(/#.*$/,""),T=new RegExp(c(i[y+1])),E=f(T,[_]);g={url:_,func:"",args:[],line:E?E.line:o[1],column:null}}if(g){g.func||(g.func=s(g.url,g.line));var k=a(g.url,g.line),A=k?k[Math.floor(k.length/2)]:null;k&&A.replace(/^\s*/,"")===i[y+1].replace(/^\s*/,"")?g.context=k:g.context=[i[y+1]],h.push(g)}}return h.length?{mode:"multiline",name:e.name,message:i[0],stack:h}:null}function y(e,n,t,r){var i={url:n,line:t};if(i.url&&i.line){e.incomplete=!1,i.func||(i.func=s(i.url,i.line)),i.context||(i.context=a(i.url,i.line));var o=/ '([^']+)' /.exec(r);if(o&&(i.column=d(o[1],i.url,i.line)),e.stack.length>0&&e.stack[0].url===i.url){if(e.stack[0].line===i.line)return!1;if(!e.stack[0].line&&e.stack[0].func===i.func)return e.stack[0].line=i.line,e.stack[0].context=i.context,!1}return e.stack.unshift(i),e.partial=!0,!0}return e.incomplete=!0,!1}function g(e,n){for(var t,r,i,a=/function\s+([_$a-zA-Z\xA0-\uFFFF][_$a-zA-Z0-9\xA0-\uFFFF]*)?\s*\(/i,u=[],c={},f=!1,p=g.caller;p&&!f;p=p.caller)if(p!==v&&p!==o.report){if(r={url:null,func:l,args:[],line:null,column:null},p.name?r.func=p.name:(t=a.exec(p.toString()))&&(r.func=t[1]),"undefined"==typeof r.func)try{r.func=t.input.substring(0,t.input.indexOf("{"))}catch(e){}if(i=h(p)){r.url=i.url,r.line=i.line,r.func===l&&(r.func=s(r.url,r.line));var m=/ '([^']+)' /.exec(e.message||e.description);m&&(r.column=d(m[1],i.url,i.line))}c[""+p]?f=!0:c[""+p]=!0,u.push(r)}n&&u.splice(0,n);var w={mode:"callers",name:e.name,message:e.message,stack:u};return y(w,e.sourceURL||e.fileName,e.line||e.lineNumber,e.message||e.description),w}function v(e,n){var t=null;n=null==n?0:+n;try{if(t=m(e))return t}catch(e){if(x)throw e}try{if(t=p(e))return t}catch(e){if(x)throw e}try{if(t=w(e))return t}catch(e){if(x)throw e}try{if(t=g(e,n+1))return t}catch(e){if(x)throw e}return{mode:"failed"}}function b(e){e=1+(null==e?0:+e);try{throw new Error}catch(n){return v(n,e+1)}}var x=!1,j={};return v.augmentStackTraceWithInitialElement=y,v.guessFunctionName=s,v.gatherContext=a,v.ofCaller=b,v.getSource=t,v}(),o.extendToAsynchronousCallbacks=function(){var e=function(e){var t=n[e];n[e]=function(){var e=a.call(arguments),n=e[0];return"function"==typeof n&&(e[0]=o.wrap(n)),t.apply?t.apply(this,e):t(e[0],e[1])}};e("setTimeout"),e("setInterval")},o.remoteFetching||(o.remoteFetching=!0),o.collectWindowErrors||(o.collectWindowErrors=!0),(!o.linesOfContext||o.linesOfContext<1)&&(o.linesOfContext=11),void 0!==e&&e.exports&&n.module!==e?e.exports=o:"function"==typeof define&&define.amd?define("TraceKit",[],o):n.TraceKit=o}}("undefined"!=typeof window?window:global)},"./webpack-loaders/expose-loader/index.js?require!./shared/require-global.js":function(e,n,t){(function(n){e.exports=n.require=t("./shared/require-global.js")}).call(n,t("../../../lib/node_modules/webpack/buildin/global.js"))}});

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.

This type of blockchains can be considered a middle-ground for companies that are interested in the blockchain technology in general but are not comfortable with a level of control offered by public networks. Typically, they seek to incorporate blockchain into their accounting and record-keeping procedures without sacrificing autonomy and running the risk of exposing sensitive data to the public internet.
This construction is achieved by composing smart contracts on the main blockchain using fraud proofs whereby state transitions can be enforced on a parent blockchain. We compose blockchains into a tree hierarchy, and treat each as an individual branch blockchain with enforced blockchain history and MapReducable computation committed into merkle proofs. By framing one’s ledger entry into a child blockchain which is enforced by the parent chain, one can enable incredible scale with minimized trust (presuming root blockchain availability and correctness).
In order to spend them, you have to prove you’re entitled to do so. And you do that by providing the solution to a challenge that was laid down when they were sent to you in the first place. This challenge is usually just: “prove to the world that you know the public key that corresponds to a particular Bitcoin address and are in possession of the corresponding private key”. But it can be more sophisticated than that.
It doesn’t matter if you’re moving $1bn or 0.01c across the Bitcoin network, you get the same security guarantees.   And you pay for this in fees and time.   What if you were prepared to trade safety for speed?   Today, your only real option is to send the coins to a centralized wallet provider, whom you must trust not to lose or steal your coins. You can then do all the transactions you like on their books, with their other customers and you never need touch the Bitcoin blockchain. But now you lose all the benefits of a decentralized value-transfer network.
Because decentralization has been viewed by many as intrinsic to the revolutionary potential of blockchain, the point of private blockchains might be called into question. However, blockchains offer much more than a structure that accommodates decentralization. Among other features, their strong cryptography and auditability offers them more security than traditional protocols (although not bulletproof, as noted), and they allow for the development of new cryptocurrencies. Furthermore, voting platforms, accounting systems, and any type of data archive can arguably be optimized with blockchain technology. We are still in the early days of blockchain technology, and the power it has to reshape older systems has yet to be seen.

Necessity is the answer to that question, well for the short term anyway. Currently public & private blockchains still have a lot of challenging technological problems that need to be sorted out, with privacy and scalability being foremost. Gallactic’s blockchain can certainly help with scalability due to its multi-chain architecture that allows for massive scaling to rival and in most cases surpass other blockchains in the market with transactions at 300 per second on mainchain with the ability to scale up to hundreds of thousands per second when the multi-chain model is configured for speed.