Always wondered this whenever i open my screw driver box.
In: 19
They were invented over time to overcome the drawbacks of other types. The slot type is the oldest and was in use for many centuries. I believe the phillips came next which improved in the slotted. After that came all the others over the last 100 years. Robertson and torque heads were to improve on the Phillips head and most of the others were originally for proprietary use that were eventually copied.
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