Which of the following programming languages is commonly used for server-side development?

When it comes to server-side development, several programming languages are widely used, each with its strengths. The most common ones include:

1. JavaScript (Node.js): With the advent of Node.js, JavaScript has become a popular choice for server-side development, allowing developers to use the same language for both client and server.

2. Python: Known for its simplicity and readability, Python offers frameworks like Django and Flask, which are robust for building server-side applications.

3. Java: A long-time favorite in enterprise environments, Java is used for building scalable and reliable server-side applications with frameworks like Spring.

4. Ruby: Primarily used with the Rails framework (Ruby on Rails), Ruby is known for its convention over configuration philosophy, making it easy to develop applications quickly.

5. PHP: Historically one of the most used languages for web development, PHP is specifically designed for server-side scripting and remains popular for dynamic content generation.

6. C#: With the ASP.NET framework, C# is used extensively for building server-side applications, particularly in Windows environments.

In summary, the choice of programming language for server-side development often depends on the specific requirements of the project, the team's expertise, and the existing technology stack. Each language has unique advantages that cater to different development needs.