Blockchain Basics

What is a blockchain?

Basics

Cryptocurrencies and blockchains are very important topics since Bitcoin’s launch in 2009. The first real-world Bitcoin transaction was made in 2009 to buy two pizzas for 10,000 Bitcoins, which are now worth more than 62 million US Dollars. In December of 2017 Bitcoin’s price reached its top with a price of $19,783 per Bitcoin. However, not only the value of Bitcoin increased significantly. Ethereum and many other cryptocurrencies took the original concept of a blockchain and extended it with features like smart-contracts and decentralized apps. But why are cryptocurrencies so revolutionary? Also, what is a blockchain and how does it work?

Bitcoin chart

Bitcoin chart // Source: coinmarketcap.com

 

Why are cryptocurrencies so revolutionary?

 

The functions of money

There are three functions or services that money has to provide. Money has to serve as a medium of exchange, as a store of value and as a unit of account.

The first and most important function or service is medium of exchange. Without money, transactions would have to be conducted by the exchange of goods. But in order to buy a good or service from somebody, you have to own a good or service of equal value. This is a major problem that is solved with money as a medium of exchange which is accepted by all parties.

The second function is store of value. Money must hold its value over time in order to be a medium of exchange. As a store of value, money is not unique. There are several other stores of value like property, stocks and so on. However, money is more liquid than most other stores of value as it is a medium of exchange that is accepted everywhere.

The third and final function is unit of account. With money being accepted as a medium of exchange, it provides a measurement of goods and services being exchanged.

 

From barter to bitcoin

In history, there were several forms of money like gold, commodity money or fiat money, which is the form of money we use today. Even though gold is a good store of value, it is very hard to transport because of its weight and its even more difficult to split an ounce of gold into two pieces. Commodity money is paper money that is linked to an amount of gold. This makes it easier to transport and better to split than gold.

So why do we use fiat money today, when commodity money is already a great medium of exchange, store of value and unit of account? In 1973 the link between gold and money was removed. Banks weren’t allowed to exchange gold ounces for commodity money anymore. This new form of money is called fiat money. Central banks around the world can print fiat money which is not linked to gold or any other goods. So fiat money relies solely on the trust that we put in central banks.

 

Why use cryptocurrencies?

Unlike fiat money, cryptocurrencies don’t rely on central institutions like banks and aren’t controlled by them. They are decentralized. Decentralized systems are accessible from everywhere, at any time and everybody can join. They have strict rules that everybody has to follow. Furthermore, decentralized systems are very hard to hack because no single institution holds the money. The most well-known form of a decentralized system is the blockchain.

Cryptocurrencies also have a limited supply. Central banks can print as much money as needed to manipulate a currency’s value. This isn’t possible with cryptocurrencies because there is no central institution that can manipulate the number of supply. Because of the limited supply, cryptocurrencies are more attractive as an asset.

Transactions on blockchains cannot be forced or reversed. Banks have control over your accounts and transactions. They have the power to deduct money from your account without your permission and they can reverse transactions. Transactions on the blockchain can’t be reversed.

 

Blockchain explain

 

A blockchain is a chain of blocks that contains information. Every block on the chain contains a number of accepted transactions and a hash of the previous block. When enough transactions are added to the block, the block will be added to the blockchain and then distributed to the network of communicating nodes running the software. The nodes need to save the whole blockchain and check every block against consensus rules. Some nodes are mining nodes. They add blocks to the blockchain by solving a mathematical puzzle and including the answer in the block. For solving this puzzle, miners receive rewards in form of coins.

 

What is consensus?

Consensus means a general agreement among the members of a group or community. In centralized systems, the consensus is reached by the central institution itself. However, in a decentralized system consensus must be reached through the whole community. In a blockchain, this mechanism is used to confirm transactions and produce new blocks to the chain. There are three consensus mechanisms.

is the oldest and most commonly used consensus mechanism. Miners create new blocks by solving a mathematical puzzle. The first miner to complete this task gets rewarded. There are advantages and disadvantages to this system. One advantage is that it is the most tested mechanism and therefore the least error-prone. However, mining becomes more and more power consuming. This makes it not only expensive but also harmful to the environment. The two most well-known cryptocurrencies Bitcoin and Ethereum utilize proof of work.

is a consensus algorithm where the validation of new blocks depends on a validator’s economic stake in the network. The blockchain keeps track of validators and anyone who holds the blockchain’s base currency can become a validator. To become a validator you have to send a special transaction that locks up your “stake” in a deposit. The higher your stake is, the easier it is to create new blocks as a validator. The biggest advantage of this type of consensus algorithm is that it is not power consuming like proof of work. Ethereum has announced that they are slowly switching their consensus algorithm from proof of work to proof of stake.

 

A fork is a change to the protocol of a blockchain. The changes in the protocol are so significant that the consensus splits in two parts. When the protocol of a cryptocurrency gets updated a soft or hard fork has to be initiated so that the changes become effective.

A soft fork is an update of the existing protocol. The old version of the protocol will still be accepted, however it doesn’t feature the functions of the new protocol. This means that a soft fork is backwards compatible.

A hard fork is like an upgrade of the blockchain. This upgrade is not backwards compatible, which means that the old version of the blockchain will not be supported after a hard fork. Furthermore, after a hard fork the community is split in two sides. The one side with users of the old blockchain and the other side with users of the upgraded blockchain.