The bottom of a wine bottle, more often than not, is not flat but deeply indented in a cone shape. Surprisingly, this odd dent prompts a frequently asked wine question: What’s it called, and what is it for?

Get ready for it: It’s called a “punt,” just like the kick on fourth down. Even more coincidentally, bottle makers call it a “kick-up,” also evocative of boot toe on pigskin.

What’s the purpose? Theories abound, as the punt goes back to the earliest days of bottle making, long before glass bottles were widely used for wine.

Some say the deep indentation makes a sturdier bottle than a simple round or flat-bottomed flask. Champagne bottles, which must withstand strong internal pressure, usually have an extra-deep punt. Other experts speculate that the dent reflects the shape of the iron rod used to hold old-time bottles while they were being blown.

And more theories abound. The crease around the punt does a dandy job of collecting sediment, prompting speculation that the form follows this function. Champagne bottles are often stacked nose-to-punt to save space in storage. And some sommeliers like to hold the bottle with thumb in punt for graceful pouring.

Finally, cynics will note that the punt, much like that extra cardboard packaging in your candy bar, makes the bottle look seductively larger than it is.

One thing is certain: There’s no real need for a punt in modern wine bottles. But like so much about wine, tradition is an important part of marketing; and consumers tend to get uneasy if we don’t get what we’re used to.