You'll find a little glass jar filled with crushed red pepper flakes in every nearly every pizza parlor across the country. This stuff is everywhere. But in a time when chiles like arbol and guajillo and ancho and other varietals get called out by name on menus, you gotta wonder: What are red pepper flakes? They're just...red pepper? You’ve shaken that little jar over a slice of pizza or some penne alla vodka or chicken parm at least once in your life (and hopefully more than that). But for an ingredient that is so widely and commonly used, what does the average person actually know about red pepper flakes? Not much at all.

Sure: Red pepper flakes are made from peppers. But how are they made? What type of peppers are used? How are they different than chile flakes? Are all crushed red peppers the same? Are those...seeds in there? We have the answers to life’s most pressing questions. (Well, at least these red pepper questions.)

Red pepper flakes are made from a mix of peppers from the capsicum annum family. Don’t get confused by the latin. You know these guys. We’re talking peppers like jalapeño, bell, Fresno, and Anaheim peppers. But the most commonly used pepper for crushed red pepper flakes is the cayenne pepper. The majority of red pepper flakes will be a mix of peppers, with cayenne taking up the majority of the share. The makeup will change, depending on which brand or company you end up purchasing.

And that’s the big difference between crushed red pepper and chile flakes. Chile flakes are generally made from a single type of pepper and used to express that pepper’s flavor. Aleppo chile flakes. Chipotle chile flakes. Urfa biber chile flakes. All single varieties used for spice and distinct secondary flavor notes. Crushed red pepper is more of a one-dimensional flavor. The primary use is to achieve heat.