Do you know when to implement IDisposable?

If you access unmanaged resources (e.g. files, database connections etc.) in a class, you should implement IDisposable and overwrite the Dispose method to allow you to control when the memory is freed.  If not, this responsibility is left to the garbage collector to free the memory when the object containing the unmanaged resources is finalized. This means the memory will be unnecessarily consumed by resources which are no longer required, which can lead to inefficient performance and potentially running out of memory altogether.

public class MyClass
{
   private File myFile = File.Open(...); // This is an unmanaged resource
}

//elsewhere in project:
private void useMyClass()
{
  var myClass = new MyClass();
   /*
  Here we are using an unmanaged resource without disposing of it, meaning it will hang around in memory unnecessarily until the garbage collector finalizes it
  */
 }

public class MyClass : IDisposable
{
  private File myFile = new File.Open(...); // This is an unmanaged resource

  public void Dispose()
  {
    myFile.Dispose(); // Here we dispose of the unmanaged resource
    GC.SuppressFinalize(this); // Preventing a redundant garbage collector finalize call
  }
}

Now we can use the using statement to automatically dispose the class when you are finished with it.:

private void useClass()
{
  using (var myClass = new MyClass())
  {
    // do stuff with myClass here...
  }  // myClass.Dispose() is automatically run at the end of the using block
}

See here for more details.