Digital currency, also known as cryptocurrency, is a type of currency that uses cryptography to secure and verify transactions as well as to control the creation of new units. There are several synonyms for digital currency, including virtual currency, electronic currency, e-cash, and cyber-currency. Virtual currency is a type of digital currency that is typically stored and traded online, while electronic currency refers to any form of online payment that doesn't involve physical cash. E-cash is a form of digital currency that is designed to be as secure as physical cash, while cyber-currency is a term that encompasses all forms of digital currency that are used for online transactions. Regardless of the term used, digital currencies are becoming increasingly popular in today's global economy.