Describe the 4 layers of the TCP/IP model

The Application layer is the first in the stack; it uses high-level protocols that set an agreed standard for the communicating end-points; related to the application used to transmit data. It does not actually determine how the data is transmitted, rather specifies the rules of what should be sent.The Transport layer uses the Transmission Control Protocol to establish an end‐to‐end connection with the source and recipient computers.  It adds the necessary information to the data packet so that it can be successfully routed and handled by the recipient.Thirdly, the Network Layer uses the Internet Protocol to address packets with the source and destination IP addresses. Routers operate on the network layer and will use these IP address to forward each packet towards an endpoint.Lastly, the Link Layer adds the unique MAC address of the physical NIC that packets should be sent to based on the source and destination IP address. This allows data packet to find the correct network using the IP address, it can then locate the correct piece of hardware.