Black Box testing

Black Box testing refers to the technique of testing a system with no knowledge of the internals of the system. Black Box testers do not have access to the source code and are oblivious of the system architecture. A Black Box tester typically interacts with a system through a user interface by providing inputs and examining outputs without knowing where and how the inputs were operated upon. In Black Box testing, target software is exercised over a range of inputs and the outputs are observed for correctness.

Advantages

a. Efficient Testing — Well suited and efficient for large code segments or units.
b. Unbiased Testing — clearly separates user's perspective from developer's perspective through separation of QA and Development responsibilities.
c. Non intrusive — code access not required.
d. Easy to execute — can be scaled to large number of moderately skilled testers with no knowledge of implementation, programming language, operating systems or networks.

Disadvantages

a. Localized Testing — Limited code path coverage since only a limited number of test inputs are actually tested.
b. Inefficient Test Authoring — without implementation information, exhaustive input coverage would take forever and would require tremendous resources.
c. Blind Coverage — cannot control targeting code segments or paths which may be more error prone than others.