[Updated September 13, 2018]

What is cryptocurrency: 21st-century unicorn or the money of the future?

This introduction explains the most important thing about cryptocurrencies. After youve read it, youll know more about it than most other humans.

Today cryptocurrencies (Buy Crypto) have become a global phenomenon known to most people. While still somehow geeky and not understood by most people, banks, governments and many companies are aware of its importance.

In 2016, youll have a hard time finding a major bank, a big accounting firm, a prominent software company or a government that did not research cryptocurrencies, publish a paper about it or start a so-called blockchain-project. (Take our blockchain courses to learn more about the blockchain)

Virtual currencies, perhaps most notably Bitcoin, have captured the imagination of some, struck fear among others, and confused the heck out of the rest of us. Thomas Carper, US-Senator

But beyond the noise and the press releases the overwhelming majority of people even bankers, consultants, scientists, and developers have a very limited knowledge about cryptocurrencies. They often fail to even understand the basic concepts.

So lets walk through the whole story. What are cryptocurrencies?

Few people know, but cryptocurrencies emerged as a side product of another invention. Satoshi Nakamoto, the unknown inventor of Bitcoin, the first and still most important cryptocurrency, never intended to invent a currency.

In his announcement of Bitcoin in late 2008, Satoshi said he developed A Peer-to-Peer Electronic Cash System.

His goal was to invent something; many people failed to create before digital cash.

The single most important part of Satoshis invention was that he found a way to build a decentralized digital cash system. In the nineties, there have been many attempts to create digital money, but they all failed.

After seeing all the centralized attempts fail, Satoshi tried to build a digital cash system without a central entity. Like a Peer-to-Peer network for file sharing.

This decision became the birth of cryptocurrency. They are the missing piece Satoshi found to realize digital cash. The reason why is a bit technical and complex, but if you get it, youll know more about cryptocurrencies than most people do. So, lets try to make it as easy as possible:

To realize digital cash you need a payment network with accounts, balances, and transaction. Thats easy to understand. One major problem every payment network has to solve is to prevent the so-called double spending: to prevent that one entity spends the same amount twice. Usually, this is done by a central server who keeps record about the balances.

In a decentralized network, you dont have this server. So you need every single entity of the network to do this job. Every peer in the network needs to have a list with all transactions to check if future transactions are valid or an attempt to double spend.

But how can these entities keep a consensus about this records?

If the peers of the network disagree about only one single, minor balance, everything is broken. They need an absolute consensus. Usually, you take, again, a central authority to declare the correct state of balances. But how can you achieve consensus without a central authority?

Nobody did know until Satoshi emerged out of nowhere. In fact, nobody believed it was even possible.

Satoshi proved it was. His major innovation was to achieve consensus without a central authority. Cryptocurrencies are a part of this solution the part that made the solution thrilling, fascinating and helped it to roll over the world.

If you take away all the noise around cryptocurrencies and reduce it to a simple definition, you find it to be just limited entries in a database no one can change without fulfilling specific conditions. This may seem ordinary, but, believe it or not: this is exactly how you can define a currency.

Take the money on your bank account: What is it more than entries in a database that can only be changed under specific conditions? You can even take physical coins and notes: What are they else than limited entries in a public physical database that can only be changed if you match the condition than you physically own the coins and notes? Money is all about a verified entry in some kind of database of accounts, balances, and transactions.

How miners create coins and confirm transactions

Lets have a look at the mechanism ruling the databases of cryptocurrencies. A cryptocurrency like Bitcoin consists of a network of peers. Every peer has a record of the complete history of all transactions and thus of the balance of every account.

A transaction is a file that says, Bob gives X Bitcoin to Alice and is signed by Bobs private key. Its basic public key cryptography, nothing special at all. After signed, a transaction is broadcasted in the network, sent from one peer to every other peer. This is basic p2p-technology. Nothing special at all, again.

The transaction is known almost immediately by the whole network. But only after a specific amount of time it gets confirmed.

Confirmation is a critical concept in cryptocurrencies. You could say that cryptocurrencies are all about confirmation.

As long as a transaction is unconfirmed, it is pending and can be forged. When a transaction is confirmed, it is set in stone. It is no longer forgeable, it cant be reversed, it is part of an immutable record of historical transactions: of the so-called blockchain.

Only miners can confirm transactions. This is their job in a cryptocurrency-network. They take transactions, stamp them as legit and spread them in the network. After a transaction is confirmed by a miner, every node has to add it to its database. It has become part of the blockchain.

For this job, the miners get rewarded with a token of the cryptocurrency, for example with Bitcoins. Since the miners activity is the single most important part of cryptocurrency-system we should stay for a moment and take a deeper look on it.

Principally everybody can be a miner. Since a decentralized network has no authority to delegate this task, a cryptocurrency needs some kind of mechanism to prevent one ruling party from abusing it. Imagine someone creates thousands of peers and spreads forged transactions. The system would break immediately.

So, Satoshi set the rule that the miners need to invest some work of their computers to qualify for this task. In fact, they have to find a hash a product of a cryptographic function that connects the new block with its predecessor. This is called the Proof-of-Work. In Bitcoin, it is based on the SHA 256 Hash algorithm.

You dont need to understand details about SHA 256. Its only important you know that it can be the basis of a cryptologic puzzle the miners compete to solve. After finding a solution, a miner can build a block and add it to the blockchain. As an incentive, he has the right to add a so-called coinbase transaction that gives him a specific number of Bitcoins. This is the only way to create valid Bitcoins.

Bitcoins can only be created ifminers solve a cryptographic puzzle. Since the difficulty of this puzzle increases the amount of computer power the whole miners invest, there is only a specific amount of cryptocurrency token that can be created in a given amount of time. This is part of the consensus no peer in the network can break.

If you really think about it, Bitcoin, as a decentralized network of peers which keep a consensus about accounts and balances, is more a currency than the numbers you see in your bank account. What are these numbers more than entries in a database a database which can be changed by people you dont see and by rules you dont know?

It is that narrative of human development under which we now have other fights to fight, and I would say in the realm of Bitcoin it is mainly the separation of money and state.

Erik Voorhees,cryptocurrency entrepreneur

Basically, cryptocurrencies are entries about token in decentralized consensus-databases. They are called CRYPTOcurrencies because the consensus-keeping process is secured by strong cryptography. Cryptocurrencies are built on cryptography. They are not secured by people or by trust, but by math. It is more probable that an asteroid falls on your house than that a bitcoin address is compromised.

Describing the properties of cryptocurrencies we need to separate between transactional and monetary properties. While most cryptocurrencies share a common set of properties, they are not carved in stone.

1.) Irreversible: After confirmation, a transaction cant be reversed. By nobody. And nobody means nobody. Not you, not your bank, not the president of the United States, not Satoshi, not your miner. Nobody. If you send money, you send it. Period. No one can help you, if you sent your funds to a scammer or if a hacker stole them from your computer. There is no safety net.

2.) Pseudonymous: Neither transactions nor accounts are connected to real-world identities. You receive Bitcoins on so-called addresses, which are randomly seeming chains of around 30 characters. While it is usually possible to analyze the transaction flow, it is not necessarily possible to connect the real world identity of users with those addresses.

3.) Fast and global: Transaction are propagated nearly instantly in the network and are confirmed in a couple of minutes. Since they happen in a global network of computers they are completely indifferent of your physical location. It doesnt matter if I send Bitcoin to my neighbour or to someone on the other side of the world.

4.) Secure: Cryptocurrency funds are locked in a public key cryptography system. Only the owner of the private key can send cryptocurrency. Strong cryptography and the magic of big numbers makes it impossible to break this scheme. A Bitcoin address is more secure than Fort Knox.

5.) Permissionless: You dont have to ask anybody to use cryptocurrency. Its just a software that everybody can download for free. After you installed it, you can receive and send Bitcoins or other cryptocurrencies. No one can prevent you. There is no gatekeeper.

1.) Controlled supply: Most cryptocurrencies limit the supply of the tokens. In Bitcoin, the supply decreases in time and will reach its final number some time around the year 2140. All cryptocurrencies control the supply of the token by a schedule written in the code. This means the monetary supply of a cryptocurrency in every given moment in the future can roughly be calculated today. There is no surprise.

2.) No debt but bearer: The Fiat-money on your bank account is created by debt, and the numbers, you see on your ledger represent nothing but debts. Its a system of IOU. Cryptocurrencies dont represent debts. They just represent themselves. They are money as hard as coins of gold.

To understand the revolutionary impact of cryptocurrencies you need to consider both properties. Bitcoin as a permissionless, irreversible and pseudonymous means of payment is an attack on the control of banks and governments over the monetary transactions of their citizens. You cant hinder someone to use Bitcoin, you cant prohibit someone to accept a payment, you cant undo a transaction.

As money with a limited, controlled supply that is not changeable by a government, a bank or any other central institution, cryptocurrencies attack the scope of the monetary policy. They take away the control central banks take on inflation or deflation by manipulating the monetary supply.

While its still fairly new and unstable relative to the gold standard, cryptocurrency is definitely gaining traction and will most certainly have more normalized uses in the next few years. Right now, in particular, its increasing in popularity with the post-election market uncertainty. The key will be in making it easy for large-scale adoption (as with anything involving crypto) including developing safeguards and protections for buyers/investors. I expect that within two years, well be in a place where people can shove their money under the virtual mattress through cryptocurrency, and theyll know that wherever they go, that money will be there. Sarah Granger, Author, and Speaker.

Mostly due to its revolutionary properties cryptocurrencies have become a success their inventor, Satoshi Nakamoto, didnt dare to dream ofit. While every other attempt to create a digital cash system didnt attract a critical mass of users, Bitcoin had something that provoked enthusiasm and fascination. Sometimes it feels more like religion than technology.

Cryptocurrencies are digital gold. Sound money that is secure from political influence. Money that promises to preserve and increase its value over time. Cryptocurrencies are also a fast and comfortable means of payment with a worldwide scope, and they are private and anonymous enough to serve as a means of payment for black markets and any other outlawed economic activity.

But while cryptocurrencies are more used for payment, its use as a means of speculation and a store of value dwarfs the payment aspects. Cryptocurrencies gave birth to an incredibly dynamic, fast-growing market for investors and speculators. Exchanges like Okcoin, poloniex or shapeshift enables the trade of hundreds of cryptocurrencies. Their daily trade volume exceeds that of major European stock exchanges.

At the same time, the praxis of Initial Coin Distribution (ICO), mostly facilitated by Ethereums smart contracts, gave life to incredibly successful crowdfunding projects, in which often an idea is enough to collect millions of dollars. In the case of The DAO it has been more than 150 million dollars.

In this rich ecosystem of coins and token, you experience extreme volatility. Its common that a coin gains 10 percent a day sometimes 100 percent just to lose the same at the next day. If you are lucky, your coins value grows up to 1000 percent in one or two weeks.

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What is Cryptocurrency: Everything You Need To Know ...