What are Milia, what are Whiteheads? How to treat Milia?

I want to be completely clear: My results have come from six years of using retinoids and three years of using azelaic acid. Most of my before and after pictures show the power of consistent, long terms use of retinoids. That being said, my skin really levelled up when I started using azelaic acid. I didn’t even start using it because I wanted more results, I was perfectly happy with my results. But I developed perioral dermatitis and azelaic acid is a treatment for that. My skin would certainly