Define integration testing

When one piece of code, or a unit, needs to interact with another, it's an interface. When we are working on interfacing the two units, we are integrating them. Testing this integration is called an integration testing. It follows unit testing and is before system testing. Therefore it is primarily a white box technique. Please see http://en.wikipedia .org/wiki/Integration_ testing However integrating the GUI with the underlying functionality is also integration testing and is best done as a black box test