Ethereum is a decentralized platform that runs smart contracts: applications that run exactly as programmed without any possibility of fraud or third party interference.
In 2014, Ethereum founders Vitalik Buterin, Gavin Wood and Jeffrey Wilcke began work on a next-generation blockchain that had the ambitions to implement a general, fully trustless smart contract platform.
Ethereum Test Network is the public test network for Ethereum. It is a joint development effort between the Ethereum Foundation and various contributors in the Ethereum community.
The mission of the Ethereum Test Network is to provide a testing ground for new features and improvements before they are implemented on the main Ethereum network. It is also a place where developers can experiment with new ideas and applications without having to worry about economic incentives.
The Testnet was launched on March 14th, 2016. The first version of the Testnet, called Morden, was quickly deprecated due to a critical security issue. The second version of the Testnet, called Ropsten, was launched on November 3rd, 2016.
Ropsten was subsequently hard fork on November 22nd, 2016 to fix an issue with mining rewards. The current version of the Testnet is called Rinkeby and was launched on February 27th, 2017.
Rinkeby is different from other testnets in that it uses Proof-of-Authority (PoA) instead of Proof-of-Work (PoW). PoA allows for faster block times and easier mining but it also means that there is a limited number of validators or “miners”. The current list of validators can be found here: https://www.rinkeby.io/#stats
The Rinkeby faucet provides free ETH to those who need it for testing purposes: https://faucet.rinkeby.io/
What Is Ethereum Test Network? – Conclusion
The Ethereum Test Network is a public testing ground for new features and improvements before they are implemented on the main Ethereum network.
The Rinkeby version of the Testnet uses Proof-of-Authority instead of Proof-of-Work which allows for faster block times and easier mining but it also means that there is a limited number of validators or “miners”.