Chili (also chile) peppers are a family of plants in the nightshade family (like tomatoes) in the genus Capsicum, which are indigenous to South America, but were brought to Europe as a substitute for black peppercorns by a doctor on Christopher Columbus' second voyage.
While chile peppers have been consumed for nearly 10,000 years, they were at first grown as ornamental plants in Europe, though they were adopted into culinary use throughout Spain and Asia fairly quickly. Today, it is a staple in Mexican cooking, as well as in Hungarian, Thai, Indian and Vietnamese cuisine.
Cultivated chile peppers are broken down into five species which include most of common peppers. From a culinary standpoint, it is easier to categorize them into "bell", "sweet" and "hot" families.
Most chiles contain capsaicin (8-methyl-N-vanillyl-6-nonenamide), a chemical that tricks the skin into thinking it has been burned or abraded by activating VR1, a receptor found in the skin and mucous membranes. The Scoville scale classifies peppers by their heat, using a dilution in sugar syrup of different chiles judged by a panel, with higher Scoville numbers equalling a higher dilution before their heat is undetectable. The scale starts at 0 for the bell pepper, and ends at 16,000,000 for pure capsaicin. The hottest pepper on record is currently the Naga Viper, at over 1.3 million Scoville units. Compare that to the Habañero at 300,000.
Some common chile peppers include the Jalapeno, Serrano, Habanero, Anaheim, Cayenne, Tabasco, Thai, Poblano, and Wax. Chile peppers can be processed either by smoking or drying -- Chipotle peppers are smoked Jalapenos, and Ancho peppers are Poblanos that have been dried.
In cocktails, chile peppers can either be used fresh or made into tinctures that provide heat to drinks and can cut perceived sweetness. As alcohol magnifies spicyness in foods, care should be taken in using chile peppers.