ABSTRACT
This chapter discusses the characteristics of blockchain. Blockchain applications work in a decentralized manner. The nodes that are unknown to each other work together by sharing the data in the form of a public ledger. Miners solve the cryptographic puzzle for the acceptance of any block so that the block can be added to the shared ledger. Blockchain systems are classified as public, private or consortium. Financial applications in the computing domain changed the dominant type of financial transactions from cash to digital money transactions with the help of banking automation. Bitcoin is a cryptocurrency which is the blockchain implementation form of digital assets that can be used as a medium of exchange with strong cryptography features to secure financial transactions. Fair exchange is executed between players that do not necessarily trust each other. A fair exchange protocol must ensure that a malicious player cannot gain any advantage over an honest player.
