What are white-box, black-box and gray-box testing?
White Box (or glass box) testing is the METHOD of giving i/p to the system and checking how the system processes i/p to produce o/p
Black Box testing is the process of giving i/p to the system and checking the o/p of the system without bothering how the o/p is generate.
Gray Box testing is a combination of White Box and Glass Box Testing. In this, the tester has little knowledge about the internal working of the s/w; so he tests the o/p as well as process carried out to produce the o/p.