What is the main protective function of a watch case?

The primary protective function of a watch case is to protect the movement from damage. The movement, which is the intricate system of gears, springs, and mechanisms that keep time and power the watch, is highly sensitive to environmental factors such as moisture, dust, and physical impacts. The case serves as a barrier, preventing these external hazards from affecting the movement, thus ensuring the watch operates correctly and maintains its accuracy over time.

Although other aspects of the case contribute to the overall durability and functionality of the watch, such as shock resistance and enhancing aesthetics, the fundamental role is to safeguard the movement itself. This is crucial because if a watch's movement is compromised, it can lead to inaccurate timekeeping or complete failure of the watch.