This book provides an overview and introduction to signal detection and estimation. The book contains numerous examples solved in detail. Since some material on signal detection could be very complex and require a lot of background in engineering math, a chapter and various sections to cover such background are included, so that one can easily understand the intended material. Probability theory and stochastic processes are prerequisites to the fundamentals of signal detection and parameter estimation. Consequently, Chapters 1, 2, and 3 carefully cover these topics. Chapter 2 covers the different distributions that may arise in radar and communication systems. The chapter is presented in such a way that one may not need to use other references.