- I2P: Invisible Internet Project: a project meant to provide an anonymity layer, so user can communicate anonymously using a range of applications.
- Router: The core I2P software, which routes encrypted packets on the I2P network. All routers by default participate in the network, which both helps the network and provides cover traffic for any clients or servers connecting to the I2P network through the router.
- RouterIdentity: A collection of information required to communicate directly with a router, such as its IP address and listening port, public signing and encryption keys etc.
- Tunnel: An anonymous communication pathway between a client or server and the I2P network. Tunnels are unidirectional, so any one client or server must have at least two Tunnels - one for inbound traffic and one for outbound traffic.
- Destination: The cryptographic identity of a tunnel. These are the identities of clients and servers within the I2P network, and are analogous to the IP:port of a computer on the normal internet.
- LeaseSet: A collection of information required to communicate with a client or server at a particular Destination, such as the gateways of the inbound Tunnels for that Destination.