What design patterns have you applied in your recent projects?

In recent projects, I often used the following design patterns:

• Singleton — for creating a single instance of a class, for example, for database connection.
• Factory Method — for creating objects without binding to specific classes, which simplifies extensibility.
• Observer — for implementing an event-driven model, where objects subscribe to changes in others.
• Decorator — for dynamically adding functionality to objects without changing their structure.
• Strategy — for selecting an algorithm at runtime, such as different sorting or validation methods.

These patterns help write more flexible and maintainable code.