One thing that I would like to make sure you realize is that the OSI model is a concept, the layers in TCP/IP are not the OSI models layers but they do perform the tasks outlined in the OSI model. The TCP/IP layers are:
Link
Network
Transport
Application
in each of these layers are protocols used to communicate online such as TCP (sending a packet and needing comformation of it reaching where it was sent) and UDP (sending a packet and not checking to see if it reached where it was sent) protocols in the transport layer or ftp, http, dns, ect. protocols in the application layer.
