What is "black-box testing"

n. Any form of testing in which knowledge of the internals of the system being tested are unknown (and unimportant)

Black-box testing is a method of software testing that examines the functionality of an application without peering into its internal structures or workings. This method of test can be applied to virtually every level of software testing: unit, integration, system and acceptance. It typically comprises most if not all higher level testing, but can also dominate unit testing as well.