This report provides an in-depth analysis of two prominent blockchain applications: Bitcoin and Ethereum. It begins with an introduction to blockchain technology, highlighting its decentralized nature and the role of blocks in storing records. The report then delves into the field and purpose of Bitcoin, a modernized payment system, and Ethereum, a platform for building and deploying decentralized applications. It explores the working models of both, including Bitcoin's use of private keys and digital signatures for secure transactions and Ethereum's smart contracts for automating legal and contractual needs. The report also addresses scalability issues associated with Bitcoin (transaction limits) and Ethereum (uncertain scalability limits). Furthermore, it outlines the features and weaknesses of each application, such as Bitcoin's anonymity and transparency versus the lack of central control and Ethereum's decentralized platform versus its reliance on the internet. Finally, the report discusses the socio-technical aspects of blockchain applications, including cyber security and privacy concerns, and concludes with the potential for increased adoption of these technologies, provided security issues are addressed. The report is well-structured and provides a comprehensive overview of the two applications.