SCIENCE | FACTS | BEYOND | HISTORY | on Instagram: "When you insert a key, it doesn’t just turn freely. Each groove and cut is carefully designed to match the lock’s internal pins. Inside the lock are spring-loaded pin stacks. When the wrong key is inserted, the pins sit at different heights, blocking rotation. The correct key lifts every pin just enough to align them at a single line called the shear line. Once all pins are perfectly aligned, the cylinder can rotate. Turning the key moves the c