Page 1 Introduction The term Bitcoin was coined by a person or a group under the pseudoname of Satoshi Nakamoto. It is a decentralised digital payment system based on peer-to-peer network with no central authority to monitor transactions but between users directly without any intermediary. It is a type of cryptocurrency as the transactions are verified by network nodes through the use of cryptography and recorded in a public distributed ledger called a blockchain [1]. [2]. Blockchain was invented by Satoshi Nakamoto in 2008 for use in the cryptocurrency bitcoin, as its public transaction ledger It is the ingenious technology which serves as a platform for cryptocurrencies. It is based on the concept of distributed transaction ledger on a peer-to-peer network which is both public and anonymous and is not controlled by any single entity or centralized authority. It requires consensus of all the participating nodes with equal weightage in the distributed peer-to-peer network and removes the dependency on any trusted third party to verify the transactions. Rather it is based on self-regulation imposed by incentive driven Proof-of-Work and Consensus Protocol assuming that honest nodes in the peer-to-peer network always hold more than 50% of the computing resources such that any malicious node is always overpowered and placed in minority by its peers. Technology Behind Bitcoin: Blockchain Blockchain is a distributed ledger on a peer-to-peer network making use of cryptographic hash functions to prevent any alteration of data logged in the ledger. It is not controlled by a central authority but is based on replication of blocks (a record of transactions) across many computers such that each block contains cryptographic hash of previous block. Once recorded, the data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which requires collusion of the network majority [2]. American Research Journal of Computer Science and Information Technology ISSN: 2572-2921 Volume 3, Issue 1, pp: 1-8 Research Article Open Access Anam Fatima 1 , Dr. Vijay Kumar Tiwari 2 M.Tech - Computer Science and Engineering Centre for Advanced Studies, Dr. APJ Abdul Kalam Technical University, Lucknow, Uttar Pradesh anamftm14@gmail.com 1 , vktiwari@gmail.com 2 Bitcoin Cryptocurrency: A Review www.arjonline.org Abstract: Bitcoin, the term coined by a person or group pseudonymously called Satoshi Nakamoto, is considered the world’s first decentralized digital currency. Since its release in 2009, there has been tremendous growth in market value of Bitcoin, with anonymity and distributed nature removing the need for any central authority being the driving force for its popularity. The technology is relatively new and complex for a layman to understand. However, there has been enough hype about it which has drawn the attention of researchers and nemesis alike to expose vulnerabilities in the system as well as explore the future perspectives of this new concept. This paper analyses major components of Bitcoin and related concepts of Blockchain, highlighting a few security concerns/ motivation to explore the future perspectives of this technology which is being considered analogous to the Internet revolution. Keywords: Blockchain; Merkle Tree/Root; Bitcoin System; Bitcoin Mining; Proof-of-Work(PoW); Consensus; Security; Future perspectives