ASM Implied volatility

[YoungestEverFSA]

ASM p145: "Implied volatility is important because it is a quick way to describe option prices"

My question: How is it a quick way to describe option prices? Lets say I knew it was, say, .3. How does that describe the option price?

Thanks Y'all

[Abraham Weishaus]

If my broker told me: "That option is priced at an implied volatility of 0.3, but you think the volatility is 0.4, so from your perspective the option is cheap", I might consider buying it.