What is Phishing Scam?

I see this in my Hotmail junk folder. What happens to the junk mail, etc,,, when I mark it as Phishing Scam?What is Phishing Scam?
It gets reported to Hotmail's security department so they can update their spam filters to prevent more of these from getting through. You actually only receive about 5% of all spam that is sent - the filters stop most before they get to your email account so you can only imagine how much spam is actually being sent