Chiles, both fresh and dried, are the backbone of Mexican cuisine, with their unique flavors that range from mild and fresh to acidic and spicy to rich and deeply toasty.
Some chiles are used for their heat, while others are used to provide flavor to sauces, stews, and spice rubs. Fresh chiles often have vegetal or grassy flavors, with clean, punchy heat. Dried chiles tend to have deeper, fruitier flavors, with nutty or even smoky undertones.
Chiles get their heat from a compound called capsaicin, which is concentrated mostly in the inner whitish pith (called ribs), with progressively smaller amounts in the seeds and flesh. If you like a lot of heat, you can use the entire chile when cooking. If you prefer a milder dish, remove the ribs and seeds. Keep in mind, though, that even among chiles of the same variety, heat levels can vary.
Here are some of the most common chiles we use in the test kitchen, as well as others that are popular in Mexican cooking.