# What is a Design Pattern

A design pattern is a proven, named answer to a problem that keeps coming up in software design. Patterns are grouped as creational, structural and behavioral, and you've already used several without knowing their names: Singleton, Iterator, Observer, Dependency Injection and the DAO.

![Cheat sheet: What is a Design Pattern](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/be1a3224c89145579232052ab3a33e84.webp)

- Category: C#
- Level: Apprentice
- Tags: Design Pattern, Observer Pattern, OOP, Singleton Pattern, software-development, Strategy Pattern
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/design-patterns-what-is-a-design-pattern-cheat-sheet