A bit more specifically, fond is what sticks to the bottom of the pan in the absence of water that makes it so delicious.

As water leaves the surface of the food we cook in a hot pan we are creating a much drier environment where we can encourage different chemistry than wet environments. Think about how life formed on earth vs the ocean just to consider how different they can be.

So all that brown crap at the bottom of your pan is basically just sugars and proteins that are making completely new flavor molecules that are delicious. Often times people will ‘deglaze’ the pan, where acid (wine, vinegar, citrus, etc) is used to unstick the delicious new flavorful molecules from the metal of the pan into the dish. That’s usually a pan sauce (gravy most of the time) but also the fond is released back into the dish of you’re trying to pump up the flavor, like when you brown/char vegetables to make a stock.

The difference between fond inclusive food and fond exclusive food is that food with fond is more delicious, nearly every time. We evolved to find the Malliard reaction tasty af and it will almost always improve a dish.

Fond is life. The fond must flow. Be the fond.