The Bitcoin world, in my opinion offers such arbitrage opportunities. But they are not as simple to execute as it might seem at first sight. Price differences between exchanges often come for certain reasons. The speed of fiat money transfers and access restrictions are just the most striking ones. You have to find out the concrete opportunities yourself. One place to start is this thread on Bitcoin StackExchange. Also, not every opportunity is available to everyone. Go and have a look at the price differences between exchanges and check out if you can find opportunities.
Several central banks, including the Federal Reserve, the Bank of Canada and the Bank of England, have launched investigations into digital currencies. According to a February 2015 Bank of England research report, “Further research would also be required to devise a system which could utilize distributed ledger technology without compromising a central bank’s ability to control its currency and secure the system against systemic attack.”
A wallet stores the information necessary to transact bitcoins. While wallets are often described as a place to hold[91] or store bitcoins,[92] due to the nature of the system, bitcoins are inseparable from the blockchain transaction ledger. A better way to describe a wallet is something that "stores the digital credentials for your bitcoin holdings"[92] and allows one to access (and spend) them. Bitcoin uses public-key cryptography, in which two cryptographic keys, one public and one private, are generated.[93] At its most basic, a wallet is a collection of these keys.
Whenever referring to the price of Bitcoin as it relates to fiat currency, the price being discussed is almost certainly an aggregate average of the price across various exchanges’ order books. Because bids and asks are instructions executed at a certain price, a large market buy would fill through several orders at incremental price levels and subsequently move the price of bitcoin up or down.
While confidentiality on the blockchain network protects users from hacks and preserves privacy, it also allows for illegal trading and activity on the blockchain network. The most cited example of blockchain being used for illicit transactions is probably Silk Road, an online “dark web” marketplace operating from February 2011 until October 2013 when it was shut down by the FBI. The website allowed users to browse the website without being tracked and make illegal purchases in bitcoins. Current U.S. regulation prevents users of online exchanges, like those built on blockchain, from full anonymity. In the United States, online exchanges must obtain information about their customers when they open an account, verify the identity of each customer, and confirm that customers do not appear on any list of known or suspected terrorist organizations.
A small class of digital currencies known as privacy coins aims to make blockchain-based transactions untraceable. They do this by beefing up the protocols designed to obscure the identity of the sender and receiver of funds, as well as the dollar amount being sent. Yes, privacy coins have been accused of being a haven for the criminal community. However, most privacy coin and blockchain developers also suggest that this is a minute component of their community, and that nearly all members are legitimate consumers and businesses.

The Bank for International Settlements summarized several criticisms of bitcoin in Chapter V of their 2018 annual report. The criticisms include the lack of stability in bitcoin's price, the high energy consumption, high and variable transactions costs, the poor security and fraud at cryptocurrency exchanges, vulnerability to debasement (from forking), and the influence of miners.[185][186][187]
Although Bitcoin is homogenous (the same everywhere in the world), its price varies across countries and even exchanges within the same country, giving a rise to arbitrage opportunities. At one point in 2017, the Bitcoin price in South Korea was trading at a 35% premium and in India, a 20% to 25% premium. The demand and supply conditions result in some aberrations in its price.
Blockchain is going to be used for more than just currency and transactions. To give you an idea of how seriously it’s been studied and adopted, IBM has 1,000 employees working on blockchain-powered projects. They’ve also set aside $200 million for development. Financial and tech firms invested an estimate $1.4 billion dollars in blockchain in 2016 with an increase to $2.1 billion dollars in 2018.
By mining, you can earn cryptocurrency without having to put down money for it. That said, you certainly don't have to be a miner to own crypto.  You can also buy crypto using fiat currency (USD, EUR, JPY, etc); you can trade it on an exchange like Bitstamp using other crypto (example: Using Ethereum or NEO to buy Bitcoin); you even can earn it by playing video games or by publishing blogposts on platforms that pay its users in crypto. An example of the latter is Steemit, which is kind of like Medium except that users can reward bloggers by paying them in a proprietary cryptocurrency called Steem.  Steem can then be traded elsewhere for Bitcoin. 
Double spending means, as the name suggests, that a Bitcoin user is illicitly spending the same money twice. With physical currency, this isn't an issue: Once you hand someone a greenback $20 bill to buy a bottle of vodka, you no longer have it, so there's no danger you could use that same $20 to buy lotto tickets next door. With digital currency, however, as the Investopedia dictionary explains, "there is a risk that the holder could make a copy of the digital token and send it to a merchant or another party while retaining the original."
"Hexadecimal," on the other hand, means base 16, as "hex" is derived from the Greek word for 6 and "deca" is derived from the Greek word for 10. In a hexadecimal system, each digit has 16 possibilities. But our numeric system only offers 10 ways of representing numbers (0-9). That's why you have to stick letters in, specifically letters a, b, c, d, e, and f. 
However, that being said, cryptocurrencies are unique in that clever marketers can make a profit doing exactly that, giving away money. This would not be possible in other currencies, where they simply can’t be broken down small enough. The operator will usually make less than a penny. If they were forced to give you a penny or more, there’d be no way to be profitable.
Consumers increasingly want to know that the ethical claims companies make about their products are real. Distributed ledgers provide an easy way to certify that the backstories of the things we buy are genuine. Transparency comes with blockchain-based timestamping of a date and location — on ethical diamonds, for instance — that corresponds to a product number.
Bitcoin, along with other cryptocurrencies, has been identified as an economic bubble by at least eight Nobel Memorial Prize in Economic Sciences laureates, including Robert Shiller,[189] Joseph Stiglitz,[190] and Richard Thaler.[191][13] Noted Keyensian economist Paul Krugman wrote in his New York Times column criticizing bitcoin, calling it a bubble and a fraud;[192] and professor Nouriel Roubini of New York University called bitcoin the "mother of all bubbles."[193] Central bankers, including former Federal Reserve Chairman Alan Greenspan,[194] investors such as Warren Buffett,[195][196] and George Soros[197] have stated similar views, as have business executives such as Jamie Dimon and Jack Ma.[198]
A smart contract is a computer code that can be built into blockchain to facilitate, verify, or negotiate a contract agreement. Smart contracts operate under a set of conditions that users agree to. When those conditions are met, the terms of the agreement are automatically carried out. Say, for example, I’m renting you my apartment using a smart contract. I agree to give you the door code to the apartment as soon as you pay me your security deposit. Both of us would send our portion of the deal to the smart contract, which would hold onto and automatically exchange my door code for your security deposit on the date of the rental. If I don’t supply the door code by the rental date, the smart contract refunds your security deposit. This eliminates the fees that typically accompany using a notary or third-party mediator.
An online bitcoin wallet is a wallet hosted in the cloud. You access the wallet through a website, from any computer, where you can deposit and withdraw funds from your bitcoin wallet. The advantage is that you do not need to install any software on your computer or download the entire blockchain, which is currently more than 30 gigabyte. You can also access your wallet from any computer in the world. The disadvantage is that you are dependent on a third party service to store your bitcoins, which can be unstable, offline or even shut down.
With smart contracts, a certain set of criteria for specific insurance-related situations can be established. In theory, with the implementation of Blockchain technology, you could just submit your insurance claim online and receive an instant automatic payout. Providing, of course, that your claim meets all the required criteria. French insurance giant AXA is the first major insurance group to offer insurance using Blockchain technology. They’ve recently introduced a new flight-delay insurance product that will use smart contracts to store and process payouts. Other insurance companies will surely follow suit.

Traditional online databases usually use a client-server network architecture. This means that users with access rights can change entries stored in the database, but the overall control remains with administrators. When it comes to a Blockchain database, each user is in charge of maintaining, calculating and updating every new entry. Every single node must work together to make sure that they are coming to the same conclusions.
The private key (comparable to an ATM PIN) is meant to be a guarded secret, and only used to authorize Bitcoin transmissions. Thus, it’s the “private key” that is kept in a Bitcoin wallet. Some safeguards for a Bitcoin wallet include: encrypting the wallet with a strong password and choosing the cold storage option, i.e. storing it offline. In the case of Coinbase, they offer a secure "multisig vault" to host your keys, which you can sign up for. 
The price of bitcoins has gone through cycles of appreciation and depreciation referred to by some as bubbles and busts.[153] In 2011, the value of one bitcoin rapidly rose from about US$0.30 to US$32 before returning to US$2.[154] In the latter half of 2012 and during the 2012–13 Cypriot financial crisis, the bitcoin price began to rise,[155] reaching a high of US$266 on 10 April 2013, before crashing to around US$50.[156] On 29 November 2013, the cost of one bitcoin rose to a peak of US$1,242.[157] In 2014, the price fell sharply, and as of April remained depressed at little more than half 2013 prices. As of August 2014 it was under US$600.[158] During their time as bitcoin developers, Gavin Andresen[159] and Mike Hearn[160] warned that bubbles may occur.
Newer cryptocurrencies and blockchain networks are susceptible to 51% attacks. These attacks are extremely difficult to execute due to the computational power required to gain majority control of a blockchain network, but NYU computer science researcher Joseph Bonneau said that might change. Bonneau released a report last year estimating that 51% attacks were likely to increase, as hackers can now simply rent computational power, rather than buying all of the equipment.
Real money is gold, silver, precious metals and gemstones, natural resources. Paper currency and coins use to be backed by gold or one of these other material commodities and was payable upon demand to any the person who had the dollar bill or coin currency, it was once written right on the Dollar bills and it was legal tender backed by the governments’ gold reserve! But corruption on an unprecedented scale took over and the general public was tricked into accepting a false standard of the economy where people blindly trusted another system which really didn’t benefit them. Just look at all the financial and economic chaos around you that has effective your lives over many decades and the political instability growing every day!
Imagine you have a restaurant and want to encourage your customers to tip with Bitcoins, there is this nice service: bctip is a website where you can print little paper vouchers that have a certain Bitcoin balance on them. When your customer has one of these, he or she can simply give it to you or your employees and you can redeem it like a coupon.
“As revolutionary as it sounds, Blockchain truly is a mechanism to bring everyone to the highest degree of accountability. No more missed transactions, human or machine errors, or even an exchange that was not done with the consent of the parties involved. Above anything else, the most critical area where Blockchain helps is to guarantee the validity of a transaction by recording it not only on a main register but a connected distributed system of registers, all of which are connected through a secure validation mechanism.” – Ian Khan, TEDx Speaker | Author | Technology Futurist
The second piece of software needed is the mining software itself—the most popular is called GUIMiner. When launched, the program begins to mine on its own—looking for the magic combination that will open that padlock to the block of transactions. The program keeps running and the faster and more powerful a miner's PC is, the faster the miner will start generating bitcoins.
At present, social media organizations are able to freely use the personal data of their clients. This helps them make billions of dollars. Using Blockchain smart contracts, users of social media will be enabled to sell their personal data, if they so desire. Such ideas are being investigated at MIT. The aim of the OPENPDS/SA project is to provide the data-owner to tune the degree of privacy preservation using the Blockchain technology.
Blockchain can also, depending on the circumstance, be very energy dependent, and therefore costly. When transactions are being verified (which we're going to talk about in the next section), it's possible that a lot of electricity can be used. This is the case in point with bitcoin, which is why so few cryptocurrency miners actually find that validating transactions on bitcoin's blockchain is worthwhile (and profitable). 

On 3 January 2009, the bitcoin network was created when Nakamoto mined the first block of the chain, known as the genesis block.[19][20] Embedded in the coinbase of this block was the following text: "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks."[10] This note has been interpreted as both a timestamp and a comment on the instability caused by fractional-reserve banking.[21]:18
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