Blockchain is currently predominantly used in cryptocurrency networks. This technology was popularized with the advent of Bitcoin, but is used by all cryptocurrencies to ensure security and transparency. Other cryptocurrencies, like Ethereum, have made changes to their blockchain network by adding features such as Smart Contracts and Decentralized Applications (DApps).
Blockchains can also be for a variety of purposes, such as issuing and maintaining real estate titles and records, medical record keeping, tracking produce, livestock and medicine throughout the supply chain, verifying ownership or validity of assets or rights, trade finance and even voting mechanisms.