This book describes how to design software using either a structured or object-oriented design paradigm. It assumes the reader already knows how to write software code, using either Java or Python, and uses this assumption to review program design criteria. This book then transitions the reader to thinking more abstractly about software design, introducing concepts and design models when appropriate.brSoftware design is a broad and complex topic, with many opinions on what it means to design software. This book addresses these challenges by first discussing software design as a detailed representation of the internal structures and behaviors of the code. It uses a case study to illustrate design thinking, including the use of abstraction, information hiding, coupling, cohesion, simplicity, performance, and security. Once the core elements of software design have been presented, five software design topics are covered. These five topics are user interface design, quality assurance, secu