This book is first edition of the contents designed for undergraduate courses in Signals and Systems. It has been written for electrical engineering, electrical and electronics engineering, electronics and communication engineering, and computer science engineering courses. The book represents the various aspects of signals and systems in very easy and effective way. This complete book is divided into three sections. Each section has three chapters. The concepts of elementary functions and their properties are explained in Chapter 1 within Section A. In this chapter we will learn to draw the graphs of various elementary functions. Here we will also learn to apply the properties of various elementary functions in solving complex problems (in both continuous and discrete time domain). Concepts of convolution and correlation are explained in Chapter 2 within Section A. In this chapter we will learn to determine the output of a system for given input. Here we will also learn to correlate various signals. Matched filter and various equations are explained in Chapter 3 within Section A. In this chapter we will learn to determine the output of the matched filter for given finite duration and infinite duration systems. Here we will also learn to draw the waveform of the given equation and vice versa. Various types of signals are explained in Chapter 4, Chapter 5 and Chapter 6 within Section B. In this section we will learn to identify various signals and compare them. Here we will also learn to analyse various complex problems on the basis of various signals. Various types of Systems are explained in Chapter 7, Chapter 8 and Chapter 9 within Section C. In this section we will learn to identify various systems and compare them. Here we will also learn to analyse various complex problems on the basis of various systems. The goal of this book is to build the concepts of the students to analyse and solve various complex problems base on various signals and systems. Note: We will cover remaining topics (Laplace Transform, Fourier Transform, Z Transform, DFT, DTFT, FFT etc.) in Part-II of this series.