Give this paragraph about TCP/IP, what are the four abstraction laters?

Context: The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are the Transmission Control Protocol, the User Datagram Protocol, and the Internet Protocol. Early versions of this networking model were known as the Department of Defense model because the research and development were funded by the United States Department of Defense through DARPA.

The Internet protocol suite provides end-to-end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers, which classify all related protocols according to each protocol's scope of networking. An implementation of the layers for a particular application forms a protocol stack. From lowest to highest, the layers are the link layer, containing communication methods for data that remains within a single network segment; the internet layer, providing internetworking between independent networks; the transport layer, handling host-to-host communication; and the application layer, providing process-to-process data exchange for applications.

The technical standards underlying the Internet protocol suite and its constituent protocols are maintained by the Internet Engineering Task Force. The Internet protocol suite predates the OSI model, a more comprehensive reference framework for general networking systems.

Answer: From lowest to highest, the layers are:
- link layer, containing communication methods for data that remains within a single network segment (link)
- the internet layer, providing internetworking between independent networks; 
- the transport layer, handling host-to-host communication;
- the application layer, providing process-to-process data exchange for applications.