Cook up a pot of rice on the stove and you'll sometimes find, after scooping up the fluffy grains, what may seem to be an unpleasant layer of grains that are practically glued to the bottom. Some may see this as a failure and send the pot straight to the sink for soaking; others (aka those who are wiser) will see it as an opportunity.
Almost every cuisine where rice is a staple in the diet has a different name for what lies underneath. In Iran, it's tahdig. In Spain, found at the bottom of a big pan of paella, it's socarrat. In the Dominican Republic, it's concón. And in China, it's guoba. They're all ways to describe the same thing: the crispy, crunchy, toasted bits of rice at the bottom of the pan.
It's considered a good thing — the best part of the rice — and the grains are intentionally cooked in a way to achieve it. The rice is usually cooked in an aluminum, clay, or cast iron pot and prepared with a little extra cooking fat in the bottom of the pan so that the bottom of the rice toasts while the rest of it steams. Once the bottom is golden-brown and caramelized, the pan is sometimes turned upside-down on a platter to reveal the toasty crust. Other times it's simply scraped out from the bottom. And while it may take some effort to get those crispy grains loose from the pan, it's completely worth it.