TRON TRX: Testnet Release
On February 11, Lucien Chen, TRON's CTO, stated on a livestream that TRON's testnet would be launched on march 21 2018. (minute 5:12)
A testnet is an alternative cryptocurrency blockchain, to be used for testing. Testnet coins are separate and distinct from real coins, and are not supposed to have any value. This allows application developers to experiment without resorting to using real coins and not worrying about the integrity and security of the mainnet.