White-box:-with knowing the internal logic of the system or 
application


Black-box:- without knowing the internal logic of the 
system or application

Gray-box:-combination of White-box and Black-box

White box testing is nothing but glassbox tetsing.
it focus on the source code. rather then the funcnality.
in these whitebox testing it covers the entire source code 
of the system.
black box testing is nothing but funcnality testing.
it is done by the testers.
it also focuss on the funnality part of the application 
rather then the source code.

a whitebox tetsing and black box tetsing mixed is called 
gray box tetsing.

White box testing: To do white box testing,We should know 
the internal logic code of the application. Mostly done by 
developers.

Black box testing: To do black box testing, we should know 
the functionality of application. Logic code is not 
required. Testers do this testing.

White Box testing:In white box esting we check 
coding,functional path,design nof the application.

Black Box testing:Inblack box testing there is no need to 
know internal structure and coding of the appliction.

Gray Box testing:It si teh combiantion of both.Fo Gray box 
testing we need to know programing language and intenal 
structure of teh application also. In Gray box testing we 
test the application from bot the side externally and 
internally.