White box testing involves testing of internal working of an application rather testing the functionality or performance of the application. This requires programming skills as the tester is SUPPOSED to WALK through the code and the test complete program flow.

Black box testing is a software testing method where the overall functionality of the software is tested without CONSIDERING the internal working. A black box tester need not know the internal structure and need not have programming skills.

In grey box testing, tester will be partially aware about internal working and overall functionalities of the application. Tester will try to find bugs RELATED with IMPROPER internal structure or improper usage of software.

White box testing involves testing of internal working of an application rather testing the functionality or performance of the application. This requires programming skills as the tester is supposed to walk through the code and the test complete program flow.

Black box testing is a software testing method where the overall functionality of the software is tested without considering the internal working. A black box tester need not know the internal structure and need not have programming skills.

In grey box testing, tester will be partially aware about internal working and overall functionalities of the application. Tester will try to find bugs related with improper internal structure or improper usage of software.