Why do wine and champagne bottles have those indentations in the bottom?
It’s not that the sommelier can get a better grip while they’re pouring, which is probably what you’ve always heard.
It’s actually there to compensate for the pressure that the contents of the bottle go through during the corking process. The sides and bottoms of bottles are weak spots, and the indentation helps evenly distribute the pressure inside the bottle. That’s why it’s so much deeper on champagne bottles, which are under much more pressure.
Unless you’re irrationally inquisitive, there are number of features on things that you use every day that you probably never even noticed. However, these things aren’t always just for show and have an intended purpose. Lots of little things in life actually have some pretty useful tricks behind them that can significantly help us live much easier lives.