This document summarizes a lecture on computer networks from IIT Kanpur in 2006. It introduces concepts like layering, encapsulation, and end-to-end vs hop-by-hop communication in networking. Layering structures networks into logical layers that isolate functions and allow for modularity. Encapsulation involves each layer adding a header to packets. Communication can be end-to-end between applications or hop-by-hop between layers at each network node. These concepts provide the foundation for how networks are designed and operate.