Node API
Nodes are the servers that manage and maintain the dYdX network. Trading transactions are broadcast to these, which then are evaluated and eventually comitted into state by the underlying consensus mechanim. It serves both a Private API, which receives transactions signed by the user, and a Public API, available for different data queries. The Permissioned Keys API is also available.
See the guide on how to use the available Node client to learn how to connect to it.