he pond you are on) is something I work with pretty often right now, although I never knew an official name for it previously. It includes having some knowledge of the background functions and structure, particularly the supporting database. A tester could perform a test on the software at the user interface level and execute SQL queries before and after the test to verify that the appropriate change took place at the database level. This type of testing may help the tester to design more accurate tests.
Wikipedia provides a large amount of information on software testing. And, did you know there is even an Association for Software Testing? Microsoft provides some great information too. There is also a great website dedicated to software testing – Software Testing Fundamentals.