I believe most people knows what Skew is. However, I believe the term Skew is used to represent different IV comparisons at different times. For instance I think "volatility skew" means the IV difference between OTM Calls and OTM Puts roughly the same strike distance from ATM.-- I think when the term "Skew" is used Alone it means the IV difference between different strikes on Put IV, or IV difference between strikes on Call IV. This is a basic question. I could be likely wrong about my assumption. If someone knows for sure let me know.