Discusses basic definitions, important properties and results on Markov Chains giving examples to understand the intricacies of the theory of Markov Chains. This book elaborates continuous time stochastic processes for modeling purpose explaining in detail with examples and includes an application oriented chapter on how stochastic modeling throws light on physical sciences. Basics on branching processes and their applications are explained pedagogically with a view to develop modeling capacity in biological sciences. Queues are a ubiquitous part of everyday life. This volume throws light on the foundation for stochastic modeling on queues. Interestingly, it presents bulk service queues an offshoot of professor Medhi's foundation on queues. A monumental and seminal contribution of Professor Neuts on matrix geometric methods is presented in a neat form. Finally, it meticulously designs some stochastic biological models and shows how stochastic modeling can project the prosperity of biological sciences.