Implied Volatility vs Vega

The annualized standard deviation of price returns implied by the current market price of an option, derived by solving the Black-Scholes model backwards from observed market price; forward-looking measure of expected future volatility; distinct from historical volatility which measures past realized movement.

The rate of change of an option's price relative to a 1% change in implied volatility; long options have positive vega (gain value when IV rises); short options have negative vega (lose value when IV rises); the primary risk in bought options around anticipated events.