This presentation provides an overview of communication channels and modelling. It discusses different types of transmission media, including guided (wired) communication media and unguided communication media. The presentation explores the use of twisted pair cables, coaxial cables, and fibre optic cables, highlighting their advantages and disadvantages. It also covers satellite microwave, terrestrial microwave, and radio broadcast as forms of unguided communication media. The presentation concludes with tips for improving signal transmission and reducing losses in fibre optic cables.