Our sessions are role of OSI layer when we open a webpage in a real world When you are trying to open a web page on your PC this is what typically happens (I am just putting the basic concepts together for understanding, most of the steps below are much more elaborate, complicated and involves more devices, protocols & lot of other details than shown below) Each slide explanation in brief : https://techsouljours.blogspot.in/2018/03/role-of-osi-layer-when-we-open-webpage.html