Sheldon Natenberg's *Option Volatility & Pricing* (1994) — the practitioner standard text on options for over three decades, used by virtually every market-making desk and proprietary trading firm — opens with a deceptively simple observation: the price of an option is not what most retail investors think it is. Most retail investors look at an option's premium, compare it to where they think the stock might go, and decide whether the trade is worth taking. Professional options traders look at five distinct sensitivities — the Greeks — and decide whether the option's CURRENT pricing is accurately reflecting the underlying's volatility, time decay, interest-rate exposure, and the rate at which all of those exposures themselves change.

The difference between the two approaches is roughly the difference between buying a stock based on the price tag and buying a stock after reading the 10-K. The Greeks are the financial statements of an option; the premium is just the price tag.