Most people may know the "Internet of money" through Bitcoin. In fact, this idea can be traced to the early stages of the Web. HTTP even reserved a status code for digital payment. The challenging part of this idea is to transfer value between different ledgers in different entities. Blockchain technology promotes this idea through building a distributed shared ledger. The current challenge is how to achieve interoperability between different blockchain ledgers and interoperability with traditional centralized ledgers. Interledger is a protocol to connect different ledgers. This protocol uses connectors and a cryptographic mechanism such as HTLC to route secure payments across ledgers. It’s not hard to join the payment network through its suites. Interledger was first initiated by Ripple and is now steadily developed by a W3C community group.