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Thirteen years ago, Satoshi Nakamoto, the unknown person behind Bitcoin, described how blockchain technology, a distributed peer-to-peer linked structure, can be used to maintain the order of transactions avoiding the double-spending problem (Nakamoto, 2008). Bitcoin orders transactions and groups them in constrained size constructions called blocks sharing the same timestamp. The nodes of the network, called miners, are responsible for linking the blocks to each other in chronological order, with every block containing the hash of a previous block to create a blockchain. The blockchain structure represents a robust and auditable registry of all transactions (Casino et al., 2019).
Blockchains introduced serious disruptions to the traditional business processes since applications and transactions that in the past needed centralized architectures and trusted third parties to verify them, currently can operate in a decentralized way with the same level of trust. The fundamental characteristics of blockchain design provide properties like transparency, robustness, auditability, and security. The authors consider blockchain as a distributed database organized as a list of ordered blocks, although the committed blocks are immutable (Lokshina & Lanting, 2021). Researchers and developers proclaim this is ideal in the banking sector as banks can cooperate under the same blockchain as they push customer transactions. Therefore, beyond transparency, blockchain facilitates transaction auditing. Companies invest in this technology due to the potential to make their architectures decentralized and minimize their transaction costs as they generally become safer, transparent, and sometimes faster. Therefore, the blockchain is not just hype. The number of cryptocurrencies, currently exceeding 1900 and still growing, illustrates blockchain importance. This development can soon create interoperability problems due to the heterogeneity of cryptocurrency applications (Casino et al., 2019; Kale, 2020).
The landscape is rapidly changing as blockchain is used in other domains beyond cryptocurrencies, with so-called Smart Contracts (SCs) playing a central role. An SC is defined as a computerized transaction protocol that executes the terms of a contract allowing a translation of contractual clauses into embeddable code that reduces the external participation and risks. In other terms, it is an agreement between parties who do not trust each other, to ensure that agreed terms are automatically applied. Within the blockchain context, the SCs are scripts running in a decentralized way and stored in the blockchain without relying on any trusted authority. Specifically, blockchain-enabled systems supporting them allow for more complex processes and interactions, so they establish a new paradigm with practically unlimited applications. As a result, blockchain technology becomes even more relevant. The global market for blockchain technology has grown rapidly in the past three years and can exceed 39B USD by 2025 (Statista, 2020; Tandon et al., 2021). Almost 1000 (33%) of C-suite executives declared that they consider or have already been active in blockchains (Kale, 2020). Researchers and developers are already aware of the capabilities of this new technology and explore various applications across different domains. Based on intended users, the following three generations of blockchains can be distinguished: blockchain 1.0 that includes applications allowing digital cryptocurrency transactions; blockchain 2.0 that includes SCs and applications extending beyond cryptocurrency transactions; and blockchain 3.0 that includes applications extending beyond the previous two versions in domains like government, health, science, and IoT.