This is a protocol in development that is designed to create interoperability in the different blockchains, allowing each computer to communicate. It has been in development since 2014, with a fairly active community.
Its main product is its Block DX exchange, which is nothing more than a Dapp that was built under the protocol developed by the project members. It is a decentralized exchange, with an easy to use user interface.
The main problem they face is that some users are not willing to download new wallets or any full node just to make exchanges, so many would prefer fast or centralized exchanges with low fees.