Computer networks allow computers to interact and share resources by connecting them through wires, optical fibers, or wireless links. The document is an introduction to computer networks for a course on computer network coding at City University in Dhaka, Bangladesh. It was submitted by Md. Al-amin Hossen, a student in the 51st batch of the B.Sc. in Computer Science program, for the course CSE-317 taught by Pranab Bandhu Nath.