This collection of Design Pattern Interview Questions is carefully curated to help developers of all levels—junior, mid-level, and senior—master key concepts and real-world applications of design patterns. Covering essential patterns such as Singleton, Template Method, Observer, and Chain of Responsibility, it provides basic-to-advanced questions with deep explanations, practical examples, and critical scenarios. Whether you are preparing for a Java, Spring Boot, or Android interview, these questions will strengthen your understanding of object-oriented design principles, best practices, and problem-solving techniques used in modern software development.