Just like the name implies, pouch underwear are sewn in such a way that they contain your “manhood” in a sort of pouch. There are different reasons why this design may be appealing. One is that you may simply like the look of them, another may be a question of comfort. By having a separate pouch, you may be less likely to experience the sweating and sticking that can occur in hot weather, or when working out.
Pouch underwear for men examples:
Andrew Christian Men’s Almost Naked Boxer, white
Andrew Christian Men’s Almost Naked Infinity Boxer, cool blue