I wear underwear when I'm out doing something where i get really sweaty like yard work or playing golf. If i don't i end up with a rash or chaffing near my crack where cheeks rub together. Had that happen to me the day before i went to the nudist resort for the weekend. Luckily it wasn't bad and everything worked out fine. Other than that I'm commando 24/7 under my clothes.
I prefer to wear briefs most of the time when I'm dressed. For one thing I perspire profusely in that area so wearing underwear helps to prevent my pants from being sweat stained in the wrong places. One of the reasons why I switched from wearing white briefs to black. To hide those ugly stains. :)Surprising how many men have mentioned wearing underwear in this forum and related groups. I would have expected that most male nudists do not. For those of you who usually wear underwear when you are clothed, why do you do so?