Pinch gripping involves squeezing the extended fingers towards the thumb without flexing individual digits, such as you'd experience holding a textbook.
Most strength athletes use plate pinches (holding two 25 or 45 pound plates together), but there are alternatives. For example, using two dumbbells allows you to have access to a greater range of weights. That makes it much easier to progress in smaller increments.
When you think of science, the first thing that probably comes to mind is images of atrophied, goggle-wearing weaklings in white coats. Bulging muscles and inhuman strength are certainly not part of your mental image!