What the poop deck did aboard sailing ships

What was the poop deck used for on an age-of-sail warship?

It roofed the after cabins and served as a high observation position behind the quarterdeck, with a name derived from old words for the stern.

The name derives from words for the stern rather than the modern English joke it suggests. Structurally, the deck roofed a cabin or after superstructure at the rear of the ship. Its elevation made it a useful observation position above the quarterdeck where the helm was commonly worked. It was therefore a partial forerunner of the bridge, though it did not duplicate every later command function.