The Pennines are a long line of hills running down the middle of England, from near the Scottish border in the north to the middle of the country. People sometimes call them the “backbone of England”, because on a map they sit like a spine. They are hills, not giant snowy mountains like the Alps — walkers cross many of the tops — but they are high enough to change the weather: the west side is often wetter. Towns grew on both sides around wool, mills, and later walking country. We almost always say the Pennines, with the, and we treat the name as a range, not one single mountain. You will meet it on maps, in weather talk, and in writing about the north of England.