"Queuing Theory Essentials for Engineers" is a comprehensive short book that overviews the fundamental concepts of Poisson Processes, Markov Chains and Queuing Theory, offering a balanced focus on theory and practice. Designed for both students and professionals in fields like operations research, applied mathematics, and engineering, this book not only reviews basic theoretical background but also provides more than 100 problems solved step-by-step. The problems vary in difficulty, ranging from basic exercises that reinforce core concepts to more challenging scenarios that require creative problem-solving and advanced analytical skills. Each problem is accompanied by detailed solutions, guiding readers through the problem-solving process and helping them to develop a strong intuitive grasp of the material.