That was me. For example, if you have held 100 shares the stock from 60 to 85, you've got a handsome profit, but you still feel bullish on the stock so you don't want to cash in. You can then buy a put to protect yourself. 1 put represents 100 shares of stock and you choose the expiration date.
You have the 100 shares at 85 and purchased at 60. You plan to hold through February, but don't want to risk a huge 20% correction due to earnings. You can purchase 1 85 strike put with a February 18th expiration date for 5 dollars. This means that if the stock goes below 85 by February 18th, you will have locked in your 25 dollars of profit minus the 5 you spent to buy the protection. In effect, if the stock returned to 60 due to some really bad news in the steel sector, you will still have 25-5=20 dollars of profit. If, on the other hand, the stock rises to 90, you break even on the put and don't gain anything. If it rises to 100, you make only 10 dollars net due to the put.
And it should follow, if you have 200 shares, you buy 2 puts.
Not necessarily saying this is the way to go, but it's certainly an option if you are getting nervous about a correction.