For a recent party, I made home-made wine.
It was drinkable. Alcoholic-percentage remains a mystery so it may have been pink lemonade instead of a rosé!
While bottling the wine - a not-so-easy task involving an inverted vacuum corkscrew through which the cork is squeezed using lots of elbow-grease/pressure - I realised that the neck of the bottle has a purpose. This may seem extremely obvious, but I need these things pointed out to me! The neck of the bottle holds the cork.
It was when I ran out of bottles and used an ex-soft drink bottle made from glass that this lesson really hit home. The bottle was shaped thus:

Now imagine a cork in the top of that bottle... it has nowhere to sit. Nowhere to squeeze into.
This brought to mind the different shaped bottles used for different wine regions / types. And I wanted to gather them together here. Three that I know...
Bordeaux:

Burgundy:

Alsace:

As can clearly be seen in these three bottles, a cork will fit snugly in each respective neck. So clever! So under-noticed!