Firo, originally known as Zcoin, is a privacy-focused cryptocurrency launched in 2016 to address privacy concerns prevalent in the digital currency sphere. It aims to improve upon Bitcoin's shortcomings in terms of anonymity and fungibility by employing advanced cryptographic techniques. Firo utilizes the Sigma protocol, previously leveraging Zerocoin and later the Lelantus protocol, which enables confidential and untraceable transactions by breaking links between sender and receiver addresses on its blockchain. Additionally, Firo employs a hybrid Proof-of-Work and masternode network to enhance security and decentralisation while offering incentives for participation. Firo's commitment to user privacy and decentralisation makes it a unique asset in the ongoing dialogue about digital cash systems.