Cryptocurrencies have gained extreme popularity in recent years. With the advent of Blockchain technology and Smart Contracts, the need for third parties or intermediaries for regulation and management has been eliminated. This has resulted in the growing adoption of digital currency and decentralized applications based on them. This article talks about the evolution of cryptocurrency and its advancements since the idea was introduced in 1983 by David Chaum. It also states about the cryptographic principles, several layers in the Blockchain technology, the smart contracts written in Solidity on Ethereum platform, and Decentralized Applications based on them. Some of the popular cryptocurrencies including Bitcoin and other Alternate Coins are also mentioned. However, there exist several legal and regulatory issues which are associated with the use of cryptocurrencies. These issues must be taken care of before moving towards the complete acceptance of these digital currencies. Hence, such issues are also highlighted in this study. Further, cryptocurrencies have found many applications including cross-border transactions, decentralized financial systems, and supply chain tracking, which are also discussed. Finally, the history and current status of cryptocurrency in India has been explored and the platforms where investors can buy and sell them are mentioned. This paper will serve as a guide for understanding the key concept of cryptocurrency, while also highlighting its practical applications. Further, the research community can study user behaviour and market ecosystems in different cryptocurrency platforms.