What does Blockchain promise? This question is at the beginning of our nanoMooc. Contracts, transactions and related data sets are concepts, which are indispensable for our everyday life. Ownership of assets or agreements between several parties need to be documented and made transparent. The digital transformation enables new opportunities to realize these documentations, but also poses new challenges, which need to be acknowledged. Blockchain is a foundational technology which can hold up to these challenges, enabling data security and transparency while documenting transactions in a decentralized, secure, transparent and irreversible way. The development of blockchain technology underwent several stages. In 2008, the concept for the cryptocurrency Bitcoin was developed by “Satoshi Nakamoto”. The software was released and the Bitcoin network was created in January 2009. Bitcoin is called a first generation Blockchain. In addition to the financial sector, first generation Blockchains are often used in the application area proof of origin. In 2014, the Ethereum blockchain was developed. A major innovation were smart contracts that can express business logic enabling automation of processes. Ethereum is called a second generation Blockchain. These platforms are used in application areas such as Internet of Things, supply chain management and Smart Grids. The foundational blockchain technology combines methods from the research areas distributed systems and asymmetric cryptography. The Blockchain is a distributed system organized as a peer-to-peer network of computers maintaining a distributed ledger. This ledger is structured into blocks and each block contains many signed transactions. The blocks are cryptographically linked together, hence the name blockchain. A complicated consensus mechanism is used to agree upon appending a new block to the distributed ledger. The cryptographical methods guarantee immutability of the distributed ledger, which supports trustworthiness of the information stored on the blockchain. Blockchain technology promises to act as trustworthy intermediary in business processes that involve several partners. Removing an intermediary could reduce cost of transactions, could speed up business processes or could make a peer-to-peer sharing economy feasible. Distributed ledger technology could support business cases for which a proof of origin is relevant. Everledger, for example, documents ownership-related transactions for diamonds. Other use cases support the transfer of digital assets or enhance the supply chain traceability of food or other products. Blockchain could support autonomy of intelligent physical objects that is beneficial for the application area Internet of Things. For example, machines could bill their services directly to their users or even other machines. Other potential application areas of blockchain technology are the media industry, the public and legal sector, supply chain management or healthcare. In summary, the blockchain technology promises to support the digital transformation. The technology itself is currently under dynamic development. Despite this, we see in many business areas a lot of proof of concept implementations, prototypes and application systems.