A class finalizer helps the .net garbage collector to clean up resources no linger needed by your classes. Personally I use these mostly in base classes, so any derived classes are correctly disposed. Of course this also means correctly implementing IDisposable too.

The syntax of a class finalizer is

public class Base : IDisposable
{
	//SQL query object used in derrived classes
	internal SqlCommand query = null;

	//Constructor
	public BaseClass()
	{
	}
	
	//Finalizer
	~Base
	{
		Dispose(false);
	}

	//Implemtation of IDisposable
	public void Dispose()
	{
		Dispose(true);
	}
	
	//Implemtation of IDisposable
	protected virtual void Dispose(bool disposing)
	{
		if (disposing)
		{
			if (query != null)
			{
				if (query.Connection.State != ConnectionState.Closed)
				{
					query.Connection.Close();
				}

				query.Dispose();
			}
		}
	}
}

The base class can then be inherited from as follows:

public InheritingClass : Base
{
	public InheritingClass()
	{
	}
}

InheritingClass inheritingClass = new InheritingClass();
inheritingClass.Dispose()

However the .net garbage collector will also execute the finalizer code whenever it performs its cleanup operations.