There are many frameworks or technologies around blockchain: R3 (corda), Ethereum, Neo, and Nem, each one with a particular design and architecture. Throughout this book, we will focus on the blockchain technology Hyperledger (https://www.hyperledger.org/).

Hyperledger is part of the Linux Foundation, which was launched in 2016 with a technical and organizational governance structure and thirty founding corporate members. More than 230 members are now part of this initiative. This includes companies such as Cisco, Hitachi, IBM, ABN AMRO, ANZ Bank, Red Hat, VMware, and JP Morgan. Today, Hyperledger works with many projects under the same umbrella and focuses on differences in blockchain use cases, as well as covering frameworks and tools. A good description of Hyperledger projects can be found at https://www.hyperledger.org. Here, it is stated that Hyperledger incubates and promotes a range of business blockchain technologies, including distributed ledger frameworks, smart contract engines, client libraries, graphical interfaces, utility libraries, and sample applications. The Hyperledger umbrella strategy encourages the reuse of common building blocks and enables rapid innovation of DLT (distributed ledger technology)components: