Bitcoin is the first decentralized cryptocurrency. Based on a free-market ideology, bitcoin was invented in 2008 when an unknown entity published a white paper under the pseudonym of Satoshi Nakamoto.
Dogecoin is a cryptocurrency created by software engineers Billy Markus and Jackson Palmer, who decided to create a payment system as a joke, making fun of the wild speculation in cryptocurrencies at the time.
Litecoin is a decentralized peer-to-peer cryptocurrency and open-source software project released under the MIT/X11 license. Litecoin was the second cryptocurrency starting in October 2011.
Ethereum is a decentralized blockchain with smart contract functionality. Ether is the native cryptocurrency of the platform. Ether is second only to bitcoin in market capitalization.