Cryptocurrencies are digital or virtual currencies that use cryptography for security, making them difficult to counterfeit or manipulate. Unlike traditional money issued by governments _fiat currency_, cryptocurrencies operate on decentralised networks based on blockchain technology—a distributed ledger that records transactions transparently and securely. The first cryptocurrency, Bitcoin, was introduced in 2009 by an anonymous figure known as Satoshi Nakamoto. Since then, thousands of other cryptocurrencies have emerged, each with unique features and uses. Some focus on fast payments _e.g., Litecoin_, others on smart contracts and decentralised applications _e.g., Ethereum_, and some on privacy _e.g., Monero_.