The need for systems modeling arises because any real-life system is inherently complicated. It is impossible to comprehend fully the intricate interaction of any system of the real world with its environment, or to define all its components and each of its details. Systems modeling or system modeling is an artifact created by humans to define what a system is.Process algebras are a diverse family of related approaches to the study of concurrent systems. Their tools are algebraic languages for the high-level description of interactions, communications, and synchronizations among independent processes. Process algebras also provide algebraic laws that allow process descriptions to be manipulated and analyzed, and permit formal reasoning about equivalences and observation congruence among processes. Accordingly, process algebra provides a perfect method for system modeling.Operation-based single-queue SBC process algebra (O-S-SBC-PA) is one of the six specialized SBC process algebras. In this book, we use O-S-SBC-PA to achieve the robust systems modeling of a system. To see is to believe. Therefore, many examples are presented to help the reader fully understand the use of O-S-SBC-PA.