An Overview of Blockchain Technology: Fundamental Theories and Concepts: Challenges and Opportunities

A blockchain formerly known as blockchain is an interesting technology developed in 2008 to aid as the public transaction ledger for the cryptocurrency Bitcoin but then, the original effort on cryptographically protected chain of blocks implemented in blockchain was initially defined by Stuart Haber and W. Scott Stornetta in 1991. A blockchain chain can be defined as a growing list of blocks (records) or simply a chain of blocks (records) that is resilient to alteration of the information. It is a Merkle tree representation of blocks which contains cryptographic hash (timestamp, transaction data, etc.) of the former block such that the chain is resilient to alteration of the information. It is now an actively emerging technology platform for developing decentralized applications like data storage, crypto currencies, etc., in various fields like Digital Forensics, Business sectors, Biomedical engineering Smart contracts, and many more. Thus, the aim of this chapter is to provide an on overview on blockchain, distributed systems, basic concept behind blockchain, impact of blockchain on digitalization, hashing, private versus public blockchain, introduction to bitcoin blockchain, Bitcoin Mining, Ethereum and Smart Contracts, Applications of blockchain in Land Registration, E-Governance and Medical Information Systems, etc.