Explain the purpose and operation of delegates in the context of C# programming.

Delegates in C# are types that represent references to methods with a specific signature. They allow invoking methods indirectly, passing them as parameters, and implementing callbacks.

Key points:

• A delegate defines the signature of a method (parameter types and return value).
• Any method with a matching signature can be assigned to a delegate.
• They enable implementing events and the observer pattern.

Example:

public delegate void Notify(string message);

public class Process
{
    public Notify OnCompleted;

    public void Start()
    {
        // ... work
        OnCompleted?.Invoke("Process completed");
    }
}

Here, the delegate Notify is used to notify about the process completion.