I've always heard that it's better to leave zits alone because when you pop them it might leave a scar.

But what about blackheads and the dry ones that don't seem to go away on their own?

I've tried to not touch them but they don't go until you squeeze them out! I've literally had a few blackheads for years before I finally decided to squeeze them.

Every girl wants smooth skin, and those dry zits make tiny bumps on your skin if you don't squeeze them out.

And also, it's embarrassing but I have what seems like zits on my nipples, especially at the center. They aren't those swollen big zits, they are perfectly flat but you can see the white heads under the nipple skin and it can all be squeezed out. Also they keep coming back!
What are they? I've never heard of people having them. Some people talk about getting zits in blocked milk glands but I have way too many of them! I'm only 20 so I don't have breastfeeding issues.
What is this??