## 4 The Intersection of Blockchain and Distributed Systems
Cryptographic algorithms encrypt each transaction and link it to all the previous transactions, thus creating a chain. This mechanism, along with the creation of public and private keys, ensures that only authorized users can access or modify the data. This whole procedure adds an extra layer of security when conducting transactions within a distributed system. Apart from this, blockchain technology incorporates an immutable ledger, which is very difficult to alter. This feature of immutability is enforced in the entire network by using consensus algorithms that require total agreement among the nodes before any change can be applied. Immutability not only enhances the overall security of the network even further by preventing unauthorized tampering with the data but also strengthens the integrity of the entire system. Regarding fault tolerance, in traditional distributed systems, it typically involves replication and redundancy strategies managed by central controllers. However, these strategies can still be vulnerable to systemic failures and may not be entirely effective in preventing data loss during network partitions. Blockchain enhances fault tolerance through its decentralized architecture. Each node in a blockchain network maintains a complete copy of the ledger, allowing the system to continue operating even if several nodes fail. Consensus mechanisms ensure that the network can reach agreement on the state of the ledger despite individual node failures, providing robust fault tolerance [51]. Scalability in traditional distributed systems can be challenging, as increasing the number of nodes often leads to greater complexity and higher costs. Centralized databases can become bottlenecks, limiting the system's ability to handle large-scale operations. While blockchain offers many advantages, scalability remains a challenge. However, emerging solutions such as sharding, off-chain transactions, and layer-two protocols like Lightning Network are being developed to enhance blockchain scalability. These innovations aim to allow blockchain networks to handle more transactions per second, making them more suitable for large-scale applications [52]. Lastly, transparency in traditional systems is often limited, with data access restricted to certain entities. This can lead to trust issues among stakeholders, as they must rely on the central authority to provide accurate and complete information. Blockchain offers a public ledger, which is usually accessible to everyone in the network and provides transparency in every transaction and data change. This prevents secrecy in actions taken within the network, and all users within it can audit and verify each transaction independently. Furthermore, as mentioned previously, the blockchain records every single transaction with a digital timestamp and links it to all previous transactions [53]. This provides a level of traceability to the data and its history, something that can be particularly useful in industries like supply chain management, where it is important to be able to verify the authenticity and history of products. Another mechanism that adds to blockchain's transparency feature is a smart contract. Blockchain utilizes smart contracts, which are essentially self-executing pieces of code, which directly contain the terms of an agreement. They are used in order to automate and enforce contractual obligations without the use of intermediaries, enhancing the transparency of agreements and transactions within a system even further. Table 5 summarizes the differences between a traditional centralized system and a blockchain-integrated system.