Rinkeby is an Ethereum testnet. Testnets are typically used by developers to test their applications or software before deploying them in production or mainnet.

Crypto-currencies held on testnet does not contain any value. Rinkeby testnet, unlike Ethereum mainnet, is a Proof-of-Authority network, as opposed to a Proof-of Work network like Ethereum mainnet. Rinkeby has average block time of 15 seconds and average network hashrate of 0.1 Hexa hashes per second.