Core concept
In the money, at the money, and out of the money at expiration
A call is in the money when the stock is above the strike. A put is in the money when the stock is below the strike. Intrinsic value is the amount the option would be worth if exercised immediately.
Call optionStock above strike = ITM
Put optionStock below strike = ITM
Near strikeInstructions matter
Example
If a stock is $102 at expiration, a $100 call has $2 of intrinsic value per share. A $98 put has no intrinsic value at that same stock price.
Limitation
Moneyness is not the same as total profit. Premium paid, commissions, spreads, taxes, and assignment/exercise handling still matter.
Primary reading: OIC options basics and Expiration Friday · OIC exercising options · OIC options exercise FAQ · FINRA options overview and expiration risk · OCC Options Disclosure Document