Girls, Women, what practical things should guys know about periods?

I live in the USA and periods are basically not allowed to be talked about. Ever. I've had 6 relationships and will even go down on women who are on their periods, but I've never actually talked about them, you know?

What are some common medications that women buy for their periods? Is Tylenol ok? Will candy help?

Between tampons and pads, should I basically just ask a girlfriend for an online picture or old package of what kind of products she wants me to buy when she needs me to?

What sorts of questions can a boyfriend comfortably ask you about your periods? What about a normal guy friend? A stranger?

Any other random, useful advice that you wish guys knew about periods would be awesome!
Girls, Women, what practical things should guys know about periods?
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