Define White box testing

White box testing method deals with the internal logic and structure of the code. White box testing also called as glass, structural, branches, paths, statements and internal logic of the code etc.  In order to execute white box testing, the tester has to deal with the code and as is required to possess knowledge of coding and logic i.e. internal working of the code. White box test also requires the tester to look into the code and find out which unit/statement/chunk of the code is malfunctioning. White box testing is applicable at unit, integration and system level though it is mainly done at unit level