Block box testing is nauthing but testing the S/W without 
know any internal structure of the S/W(Coding).Testers will 
do this.
what is the confusion in this
it is one of the testing methodologies

Whitebox testing - done by developers while they are coding 
an application. Ex - Unit testing.

BlackBox - Testing the actual application...it aims at the 
resuls given by the application. Ex, Func, system, 
integration etc., comes under this.

Black box is data driven, or input/output driven testing

The Test Engineer is completely unconcerned about the
internal behaviour or structure of program.

It is also known as behaviour, functional, opaque box and
closed box testing

Black box testing is testing the application without having 
any knowledge on internal logic . To be simple, Testing the 
output by giving inputs.

Testing software without any knowledge of the back-end of 
the system,structure or language of the module being 
tested. Black box test cases are written from a
definitive source document, such as a specification or 
requirements document

Now is it clear 

If i m Wrong pls correct me 
er4testing@yahoo.com

In Black Box testing the tester only knows what the sotware
is supposed to do...he can't look in the box to see how it
operates.If he type in  certain input he gets a certain
output .........

Example:::: Think about the windows calculator ..if u type
3.14159 and press the sqrt button ,u get 1.7724531. with
black box testing it doesn'tr matter what gyrations the
software goes through to compute the square root of pi. It
just does it.   bye.............