A C# developer should be familiar with several development methodologies, particularly Agile and Scrum. These frameworks allow for collaborative work in sprints, where developers can deliver small, iterative chunks of code, continuously improving the product. Familiarity with Waterfall methodology may still be useful, particularly in more traditional industries or legacy systems, but Agile is far more common today. DevOps practices, which focus on continuous integration, continuous delivery, and automation, are also becoming increasingly important, especially for larger teams and projects. Test-Driven Development (TDD) is another valuable methodology, as it ensures that developers write code that is both functional and thoroughly tested before it’s deployed.