The flintlock marked a great achievement in firearms manufacturing. This firearm became the standard of use in the mid- to late- 1600's and were used well into the 1800's. They are still used today by some muzzleloader hunters.
When you pull the trigger on a flintlock, the flint (a quartz stone) strikes against a steel frizzen, creating a shower of sparks that ignite the priming charge in the flash pan. You'll notice that this is rifle is starting to look like modern-day firearms. It was the first to have a hammer as part of the firing mechanism.