The book gives an insight study to what signals and systems are, their nature, behaviour, analyses, classifications, relationships, applications and inter-relationships with mathematics. Signals play very significant roles in the study/analyses of systems of whatever type. Systems themselves have to be identified using signals and understood before they could be used for any purpose. It can then be seen that the two are symbiotically related. It is recommended that students would have taken basic Engineering Mathematics course, including differential and difference equations before reading this book. It would be suitable for students studying for B.Sc. degree in Electrical, Electronic, Computer or Communications Engineering.