In options trading, the mark is the price at which a particular option is trading at. The mark can be affected by a variety of factors, including the underlying stock price, the current market conditions, and the amount of time until expiration. When making decisions about options trading, it is important to keep an eye on the mark in order to make sure that you are getting the best possible price. With a little practice, you will be able to quickly identify when the mark is favorable for buying or selling options.