When choosing the perfect pair of mountain boots, it is important to determine which category of boot you will require. These categories are defined by letters: B, B/C, C, and D.
Category B and B/C
Hiking boots in this category tend to be a bit stiffer and more strong than boots in categories A and A/B. These boots are made for mountainous terrain where you might wear a heavier backpack and hike on more challenging trails or terrain.
Category C and D
These categories of hiking boots are suitable for heavy hiking in the mountains, for example, a multi-day hike in the Alps. The shoes have a stiff sole that is suitable for flexible crampons. The boots are also suitable for rock climbing. Using these boots for a flat-terrain walk is not recommended, as the stiff sole makes normal foot motion almost impossible on flat ground.