### Instruction: What is a automatic winding mechanical watch?
### Response: A mechanical watch utilizes a non-electronic mechanism to provide the time of day.  A mainspring is used to store energy in order for the mechanism to operate.  An automatic winding mechanical watch utilizes a free rotating weight to wind the mainspring as the watch is worn on the wrist.  In contrast, a manual winding watch requires the wearer to manually wind the mainspring.