A screwdriver is classified by its tip, which is shaped to fit the driving surfaces (slots, grooves, recesses, etc.) on the corresponding screw head. The two most common are the simple 'blade'-type for slotted screws, and Phillips, generically called "cross-recess", "cross-head", or "cross-point". Patented in Portland, Oregon, by Henry F. Phillips, the early version of the Phillips screw consisted of a deep socket with a cruciform slot. With the Industrial Revival at the end of the Great Depression and the upheaval of World War II, the Phillips screw quickly became, and remains, the most popular screw in the world. A main attraction for the screw was that conventional slotted screwdrivers could also be used on them, which was not possible with the Robertson Screw.

Source: Wikipedia