TCP+IP

The Forth of these layers is **application layer** this specifically identifies certain protocols such as FTP, Telnet and HTTP (Hyper Text Transfer Protocol) this contains all the process to process protocols.

The Third layer of these is the **transport** **layer** this provides end to end communication for the application layers this controls one of the most important procedures of all resending lost or damaged packets if this was not built in then it would be bad as when an email is sent it goes into loads of little packets if one of these was lost then pieces of the email would be lost. This layer utilises TCP and UDP ( With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an IP network without having to set up any special transmission channels or data paths. In a nutshell, this layer breaks down web pages, emails and other documents into smaller segments for sending.

The Second layer, the **Network/ Internet layer** is very important and actually has the name of shared TCP/IP this stands for internet protocol this is vital in sending an email as it decides what gateway to put it on and then this makes no guarantee that the packets will arrive at the intended address. But it makes a best effort, the guarantee is by the transport layer.

The First is the **link/network interface layer** and this is used to transfer the packets from one host to another host and this is done through the internet layer on the same link.This layer manages the addressing of data packets by adding the IP address (Internet Protocol).