What is the role of interfaces in software development?

Interfaces in software development serve to define a contract — a set of methods and properties that a class must implement, without specifying the concrete implementation. This allows:

• Ensuring loose coupling between components.
• Simplifying the replacement and extension of functionality without changing the code that uses the interface.
• Supporting polymorphism, enabling working with different implementations through a common interface.

In C#, an interface is declared using the interface keyword and can contain only method signatures, properties, events, and indexers.

Example:

public interface ILogger
{
    void Log(string message);
}

public class ConsoleLogger : ILogger
{
    public void Log(string message)
    {
        Console.WriteLine(message);
    }
}

Thus, interfaces help build flexible and extensible architectures.