The oldest pocket knife, or "jack knife," ever discovered dates back to around 600-500 BC. It was unearthed in Hallstatt, Austria, and it features a single blade with a bone grip.
Romans were the next group to really use the pocket knife as a tool. Many folding knives made of iron with bronze handles have been discovered from the Roman Empire. These knives did not have locks or springs, but rather used resistance to stay closed and required force from the hand or thumb to remain open. The first notable back-spring knife was invented between 1650 and 1700 by cutlery centers in Sheffield, England.