Funny, but to me I find the fine line being drawn between underconfidence and overconfidence.

I view a confident man as stoic - he knows his place in the world, what he's capable of, what his limits are, and doesn't have anything to prove to anyone else. He is most comfortable around others who are both confident and self-sufficient as well. He can be relied on, but not taken advantage of. He is quietly content with himself, and doesn't find the need the world to revolve around him.

Egotistical, self-centered men might exude confidence, but whether it's a result of narcissism or is a facade used to hide feelings of inadequacy, insecurity or unworthiness isn't clearly evident until the person is known better (Any takers? :-). These are the guys who always seem to be trying to prove their manhood, they tend work hard at remaining the focus of the conversation, try to control every situation they're in, always seems to need to have their way. They're also very quick to cut down others, and can be insolent, pushy and brass.

exactly

confidence doesn't intimate me. I have met men who were delighted by that, or disturbed by it, or some odd combination of both. Confidence is one of those things that's important to being attractive...but not enough on it's own. A man could be very confident in alot of ways and still not be my thing. Maybe that's due to the same reason why it doesn't intimidate me. It isn't a mystical magical thing to me. I think sometimes people who don't feel very confident do imagine confidence is some mystical thing, or is attributed to being something more than they can be or are, which is probably why it makes them think someone with it is different from them, above them, better than them or whatever. I think people do the same thing with fame and money and high IQ and charisma and classical physical beauty now that I think about it.

I have met more men who were really insecure...acting as they thought a man with confidence would act and they did not intimidate me either. They were also not the least bit attractive to me and usually irritating and occasionally creepy. Come to think of it I usually go for men who are secure in some areas and not so much in other areas...because that feels natural to me. It's like fifi said an accurate accountability of talent and ability as opposed to an "attitude" they put on in everything they do. Yeah that is totally how I am. I am attracted to men who have an accurate understanding of themselves to a great extent. Not ones who are sure they are the most fantastic ever in all things, or somehow above me and not ones who can't see their good qualities no matter what. Bleh.

I'd totally pick a guy who was a bit lower in confidence than a guy with a bit more but who tried to blow it up into something bigger or wear it like personality bling or some other pretentious crap.

Confidence does not intimidate me in the least.

yes Confidence is required in a man for me to be interested. What I am looking for is a man who says with his body language, his life, everything " I can handle anything that comes my way" and more specifically " we can handle anything that comes our way". That confidence is a turn on. It means he is taking care of himself so well, he is ready to try taking care of a relationship and family.

Women must be better people in some ways than men. It seems we like men who are confident and healthy and smart. We encourage it. Men sometimes prefer a women who is not as smart or as confident as he is ( Actually women do this too. ) I wrote about that study that showed that men don't date women they find smarter or more ambitious than themselves on average.
It may just be the confident among us who prefer confident partners. Who would want an insecure person unless they were insecure themselves?

the key to confidence seems like an excellent question.

My first thought is that it is the ability to see yourself and others clearly and objectively and accept what you see.