Can you explain the meaning of interfaces in object-oriented programming?

In object-oriented programming, an interface is a contract that defines a set of methods without their implementation. Classes that implement the interface are required to provide a concrete implementation of these methods.

Interfaces allow:

• Defining common capabilities for different classes.
• Ensuring polymorphism — objects of different classes can be used through a common interface.
• Separating definition and implementation, which improves modularity and testability.

Example in C#:

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

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

Here, ILogger defines the Log method, and the ConsoleLogger class implements this method.