They use scarves, hats, wigs, and (ugly) snoods. Depending on the community, some wear only scarves, only wigs, only hats, and even only wigs with a hat on top. I never understood that one - it seemed kind of deceptive to me to be wearing a hat on top of a wig, which could be mistaken as the real hair that the woman is trying to cover with her hat.
Personally, I like hats. Not for covering my hair (unless you count bad hair days) but just because I like hats.
That doesn't mean that when I get married I'm going to wear hats to cover my hair; in fact, I plan to wear -- very expensive, very authentic-looking -- wigs when I get married.
But you can't say, "I like hats," in the frum community without getting a barrage of comments about covering your hair for marriage.
Case in point: I visited some cousins in Israel during the summer a few years ago and happened to be wearing a hat. It was sunny and the hat was cute, so I wore it. As girls tend to do, I asked my cousin, "So, how does this hat look?" and instead of telling me whether she liked the hat, she said:
"Don't wear it. You look married."
Seriously? I'm supposed to give up wearing hats because someone might mistake me for being a married woman? Oh, the horror.
I haven't given it up, and neither have the double-takes that people I know give me when they see me wearing a hat. Just a few weeks ago I was wearing a hat in the supermarket and bumped into the husband of a friend of mine. It was raining hard that day, which should have been enough to keep him from standing there blinking at me owlishly, but it wasn't.
"Did you get married?" he asked me.
"Nope. It's raining. I like wearing hats," I answered him. "And that's hat discrimination!"