I'm a little confused on how options trading works, namely what you are selling when you sell an option.
Let's say you buy a put option for 100 shares at a strike price of $100 for a company XYZ that has a stock price of $100. If you believe the price will go up to $120 and sell the option for a premium of $50, are you then responsible if the person to whom you sold the option exercises it? Or is the option writer the one who has to buy the 100 shares from the person you sold the option to at the strike price of $100?
Any help is appreciated