Hello, I was wondering if someone can explain to me what x% implied volatility means. For example, this article uses it to talk about BAC: http://finance.yahoo.com/banking-budgeting/article/113376/options-trader-bet-big-bofa-barrons. I've always understood implied volatility to be the extrinsic value of an option, which should be the market price of an option when it is out of the money. But how do they calculate the implied volatility % and what does it as a % mean? Thanks.