TETHER tokens exist as digital tokens built on Bitcoin (Omni and Liquid Protocol), Ethereum, EOS, Tron, Algorand, BCH, OMG and Hermez Network blockchains. These transport protocols consist of open source software that interface with blockchains to allow the issuance and redemption of cryptocurrency tokens, in this case, "tethers."
TETHER token was originally created to use the Bitcoin network as its transport protocol—specifically, the Omni Layer—to allow transactions of tokenised traditional currency. Since this original version of the TETHER token uses the Bitcoin blockchain, it inherits the inherent stability and security of the longest established blockchain network.
TETHER token on the Ethereum blockchain, as an ERC20 token, is a newer transport layer, which now makes tether available in Ethereum smart contracts or decentralised applications on Ethereum. As a standard ERC20 token it can also be sent to any Ethereum address.
Since TETHER tokens are currently available using different transport protocols, when users send TETHER tokens to other addresses, they need to carefully check the destination address to confirm they are selecting the correct transport protocol.