Design Patterns in Software Development: Understanding and Implementing Common Solutions

Explain what design patterns are and why they matter in software development. Then cover [number] common patterns: [pattern 1], [pattern 2], and [pattern 3]. For each pattern: 1. Problem it solves with a real-world analogy 2. Structure/components with a UML-style diagram 3. Implementation example in [programming language] with detailed comments 4. Practical use case from a real application 5. Pros, cons, and when NOT to use it 6. Common variations or related patterns Conclude with guidelines for recognizing when to apply each pattern in your code.