Most cryptocurrencies (including Monero) use a distributed ledger (called a @blockchain) to keep track of previous transactions. The blockchain serves to tell other users on the network that transactions have happened. There are many different ways for cryptocurrencies to create their blockchain, and not all are the same. Monero uses proof-of-work to craft blocks, where other cryptocurrencies may use proof-of-stake or other consolidated methods.
Ultimately, cryptocurrency is an attempt to create trustless value; that is free from borders, governments, and banks. Whether that be to transact or to be digital gold is up to the users of each.
