Abstraction Layers

Application.		Application.
Transport. TCP, UDP.		Transport. TCP, UDP.
Internet. IP.		Internet. IP.
Host-to-network. Ethernet, FDDI.

The Open Systems Interconnection (OSI) 7-level model is overkill since many layers collapse into one or don't exist.
Host-to-network defines how a particular network interface (Ethernet card, PPP connection) sends IP datagrams over its physical connection. Examples: Ethernet, Token Ring, LocalTalk.
A gateway can convert from one interface to another.