What are design patterns?

Design patterns are proven solutions to common problems that arise during software development. They are templates that help structure code, improve its readability, reusability, and maintainability.

Main categories of patterns:

• Creational — manage object creation, e.g., Singleton, Factory Method, Builder.
• Structural — define how classes and objects are combined to form larger structures, e.g., Adapter, Decorator, Composite.
• Behavioral — describe interactions between objects and the distribution of responsibilities, e.g., Observer, Strategy, Command.

Using patterns helps avoid reinventing solutions, makes architecture more understandable, and facilitates code maintenance.