The main topic of the book is the use of Polymer Optical Fibres for data communication. The first two chapters describe the basic physics of optical fibres and the specific properties of POF. The next chapters summarise the history of POF development, including the explanation of different index profiles from the simple step index type to the graded index POF. The next three chapters give comprehensive review of sources for POF systems and published transmission systems including WDM and analogue systems. The calculation of power budgets is described, giving some examples and general formulas and guidelines. Measurement techniques and standards are the content of further chapters, closing with remarks on international POF activities.