The fourth topic is all about blockchain platforms. In this first part, we are going to identify some of the most popular blockchain infrastructures, which we are then going to compare in the second part. The first and probably most known blockchain infrastructure is the Bitcoin platform, which was developed by Satoshi Nakamoto in 2009. It is public, meaning that everyone who downloads the blockchain can read all transactions. Also, it is permissionless, so there is no registration needed to join the blockchain. The native cryptocurrency of the blockchain is Bitcoin. Mining and trading this currency is the only purpose of the Bitcoin blockchain. A different blockchain infrastructure is the Ethereum blockchain. The Ethereum blockchain is also public and permissionless, so everyone can download the blockchain, make transactions and read other transactions without any restrictions. The native cryptocurrency is Ether, but besides currency exchange, smart contracts can be implemented to automate processes other than currency exchanges. Hyperledger Fabric is a third well known blockchain implementation, which provides the user with the ability to customize parts of the blockchain, like the consensus mechanism, thanks to a modular architecture. It is a private, permissioned blockchain, which means that users need to register to be part of the blockchain and cannot use a pseudonym. Furthermore, reading access can be restricted to chosen members of the blockchain, so transactions are not transparent to everyone on the blockchain. Hyperledger Fabric has no native cryptocurrency, however, cryptocurrencies can be added. Similar to the Ethereum blockchain, smart contracts can be incorporated into applications based on Hyperledger Fabric, and it is, like Ethereum, a generic blockchain, so it is not limited to a specific industry. Next to Bitcoin, Ethereum and Hyperledger Fabric there are other blockchain alternatives and implementations They use advanced technology based on blockchain. R3 Corda is a blockchain implementation which is specifically designed for the financial services industry. It is private and permissioned, like Hyperledger Fabric, but it does not provide any cryptocurrencies. Furthermore, smart contracts in Corda also contain legal prose to fit into the highly regulated financial environment. Iota does not use blockchain technology, but a directed acyclic graph as a data structure, the tangle. Iota was developed to support the Internet of Things and facilitate machine-to-machine transactions. There is no mining to validate transactions, but each device wanting to make a transaction also needs to validate transactions. Other than blockchain technologies, Iota is not open source. Hashgraph is another alternative to blockchain technology and provides a faster and more efficient technology for cryptocurrency exchange. As opposed to other blockchain implementations, the order of the transactions cannot be manipulated, no transaction can be delayed or denied to be added to the blockchain and nodes in the network do not need to store all past transactions, but only the current balance of each wallet, leading to decreased storage needs. This figure puts the presented blockchain infrastructures and alternatives into comparison. The comparison is based on their access restrictions and whether they are logic oriented or transaction oriented. Ethereum, Hyperledger Fabric and R3 Corda are all logic oriented, but while Ethereum is an unpermissioned blockchain, Hyperledger Fabric and R3 Corda are permissioned. Bitcoin, IOTA and Hashgraph are transaction oriented and permissionless. In this topic we have learned about different blockchain infrastructures. The three most popular infrastructures are Bitcoin, Ethereum and Hyperledger Fabric.
