Dried chiles are fresh chile peppers that have had most of their moisture removed, by sun-drying or mechanical dehydration, which concentrates their heat, flavor, and natural sugars. Drying was originally a preservation method and remains central to Latin American and many Asian cuisines.
Common varieties include ancho, chipotle, pasilla, guajillo, New Mexico, and árbol chiles, ranging from mild and fruity to fiery and smoky. Heat level, measured on the Scoville scale, varies widely by variety, so quantities should be adjusted accordingly - mild anchos and pasillas can be used more liberally, while fiery árbol or Thai chiles should be used sparingly.
In cooking, dried chiles are typically rehydrated in hot liquid and puréed into sauces, moles, and marinades, or toasted and ground into chili powder and spice rubs. Whole dried chiles are also used to infuse oils and broths. They are essential to Mexican mole and enchilada sauces, and to chile-based pastes in Indian and North African (harissa) cooking.
Store dried chiles in an airtight container in a cool, dark place; they lose potency and aroma over time.