Our eyes don't view the world vertically or horizontally. Instead, we see panoramas. Heretofore, trying to photograph the same way we see by making panoramas required either special equipment or manipulation of the negative or slide. Medium format 6x17 cameras, such as the Fuji or the Linhof , cost many thousands of dollars for a body and a few lenses but produced stunning results. Special 35 mm cameras with the same aspect ratio could deliver panoramas with modest resolution. Digital photography, by contrast, allows us to stitch together consecutive images to create a high resolution panorama with our existing lenses and a good digital body.
As an added advantage, each element of the panorama adds information and increases the file size and thus the resolution of the finished print. You can effectively increase the resolution of your camera by stitching together three verticals side-by-side shots to create a single horizontal image. This image will have three times the resolution of a single horizontal image shot with the same camera. I use this trick when I want to carry my lower resolution (and much lighter) camera on a hike instead of my brick-heavy main body.
If you want to create a true panorama, stitch two horizontal pictures or a series of verticals. However, with vertical images the file size of your final image becomes quite large and cumbersome, especially in uncompressed formats. The upside is that these large files are ideal for very large prints.