What is a automatic winding mechanical watch?
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### 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.