So the profit is the difference between the strike price and the share price after to goes beyond your target?
Is that difference times 100?
Current stock price: $30.
Put option strike price: $20.
Stock goes down to $18.
You sell the stock option (is there another term for this?).
Profit = $200 (2 x 100) ?
No.
The profit or loss (if you sell the option) is the difference between the option price when you bought and and the option price when you sold it.
So, if the stock price is :$30
Put option at a strike price of $20 costs: $5
Stock goes down to $18
Depending on when you sell the option determines if you make a profit and how much.
Time decay hurts you.