The following is a rant. You have been warned.
When I first started in photography, well, when I got my first 35mm camera, there were two ways to orient the camera. I could make tall pictures. I could make wide pictures. This opened up some artistic possibilities which were previously unavailable to me. I had been shooting medium format prior to that, and at that time, medium format cameras primarily shot square pictures.
There were names for these two orientations of the camera. They were called "horizontal" and "vertical". They were given these names for a reason: they described the shape of the picture. And, it was obvious what they meant. The wide ones were horizontal, and the tall ones were vertical.
It was good, and I was happy. I went about making more pictures. I made portraits of people, and pictures of landscapes.
Recently (relatively recently, anyway -- I've been doing this for quite a while), I've heard people, including professional photographers who really ought to know better, talking about making "portrait" and "landscape" pictures, but they weren't talking about the content. They were talking about the orientation of the picture -- horizontal and vertical. The new implication of this terminology is that tall picture shapes are for portraits, and wide picture shapes are for landscapes, and nary the twain shall be. This is wrong.
Very often, a portrait of a person is much better if it's a horizontal. And many, many landscapes are stronger and more interesting if they're shot vertically.
So, what happened? Simply put, Microsoft happened. Specifically, Microsoft Word, and printer drivers for Windows happened. Oh, it was okay for a while. Originally, the choices in printer settings were "Tall" and "Wide". Really. But somewhere along the lines, some nincompoop at Microsoft decided that we needed better words to describe the way print appeared on a piece of paper. They looked at the picture of their wife or girlfriend on their desk, and decided that tall pictures were portraits. Then, they glanced at their calendar, and noticed the pretty picture of the mountains and decided that landscapes must be wide pictures. So, they came to the conclusion (without consulting me -- or any other photographer or artist -- I might add) that a tall picture must be called "portrait", and that a wide picture must be called "landscape", and that the name must also apply to the orientation of the paper.
And so they coded it.
People, we need to do better. We need to go back to using correct terminology. We need to promote clarity in our discussion.