Most people don't eat chilli peppers in large quantities, but the amount of vitamin C they contain is significant and red chillies (although not green ones) are full of beta-carotene. The nutritional aspect of hot peppers most interesting to researchers today, however, is capsaicin, the compound that gives chillies their "burn." Capsaicin seems to have a positive effect on blood cholesterol, and also works as an anticoagulant. And the "high" that some people experience when eating fiery chilli spiked foods is a perfectly safe one: Some scientists theorise that in response to the discomfort produced by the chillies' "burn," the brain releases endorphins, substances that, at high levels, can create a sensation of pleasure.

Members of the genus Capsicum, chilli peppers are native to the western hemisphere. Hot peppers are liberally used to add spicy heat to dishes, particularly in tropical and subtropical cuisines, especially Mexican, Caribbean, Indian, Thai, Szechwan, Vietnamese, and North African.

Chilli peppers are cultivated in a range of sizes, shapes, and degrees of hotness. While nearly all of them belong to one species Capsicum annuum, the number of varieties is daunting, and the names are confusing, as they vary from region to region.

While the following list can help you distinguish the most common chili pepper varieties, it can be tricky, if not impossible, to determine just how hot a pepper is. Capsaicin content is measured in parts per million. This measurement is converted in Scoville heat units, the industry standard for gauging a pepper's punch. One part per million is equivalent to 15 Scoville units. To put things in context, sweet peppers have 0 Scoville units, while habaneros, the hottest chili peppers, register a blistering 200,000 to 300,000 units.

Ancho: Technically, ancho refers to a dried poblano pepper, but many distributors and markets also apply the term to the fresh version. Dried anchos are flat, wrinkled, and heart shaped, ranging in colour from oxblood to almost black. Considered one of the mild to moderately hot peppers , anchos are often soaked and ground for use in cooked sauces. Scoville units: 1,000–1,500.

Cascabel: These moderately hot chillies are mostly available dried. In their fresh state, they are green or red and shaped like a small tomato. Dried, their skin turns a brownish red and becomes translucent, and their seeds rattle around inside. The name cascabel means "jingle bell" in Spanish. Scoville units: 3,000.

Cayenne: Among the hottest chillies, cayenne peppers are long, thin, sharply pointed red pods that are either straight or curled at the tip; they grow to a length of 6" to 10". (The chile de arbol is closely related and similar in shape, but grows only 2" to 3" in length and usually does not have a curled tip; it is also slightly less pungent.) Ground, dried cayenne is a popular spice. Scoville units: 30,000–50,000.

Cherry: So named for their resemblance to the familiar fruit, cherry peppers are round and red. They range in pungency from mild to moderately hot. Cherry peppers are sold fresh, and also are commonly pickled and sold in jars. Scoville units: 0-3,500.

Chile de arbol: About 3" long and 1/2" wide, this hot pepper is a good substitute for cayenne. Scoville units: 25, 000.

Chipotle: Also known as smoked jalapeno, the chipotle is medium hot with a deep, smoky flavour. Scoville units: 10,000.

Guajillo: These long peppers measure about 6" by 1 1/2" and have a sweet, medium-hot flavour. The guajillo is frequently used in Mexican cooking. Scoville units: 3,000.

Habanero: These lantern-shaped peppers, measuring about 2" by 2", are Capsicum chinense, not Capsicum annuum. Their colour is most often yellow-orange, but can be yellow, orange, or red. Habaneros hold the distinction of being the most fiery of all domesticated peppers; however, their heat can sneak up on you, so beware of taking a second bite if you think the first one wasn't hot (which is unlikely). Furthermore, rather than dissipating quickly, the heat of habaneros persists. They are also called Scotch bonnets. Scoville units: 200,000–300,000.

Hungarian wax: They are never green, the peppers start out yellow and ripen to orange or red, and are mostly sold when yellow, either fresh or pickled in jars.

Jalapeno: Probably the most familiar hot peppers, and almost as popular as the Anaheim, jalapenos are tapered, about 2" in length, and have slight cracks at their stem ends. They vary in degree of heat, sometimes tasting much like a green bell pepper and other times being very hot, with a bite that you notice immediately. Most often, these peppers are consumed at the mature green stage, but sometimes you will find fully ripe red jalapenos on the market. In addition, they are sold canned, sliced, and pickled, and are used in a wide array of products. Pickled jalapenos are always hot. Scoville units: 2,500–5,000.

Pasilla: In Spanish, pasilla means little raisin, and this pepper is so named because of its deep black colour and raisinlike aroma. It is mild with a smoky flavour. Scoville units: 2,500.

Fresh chili peppers should be well shaped, firm, and glossy. Their skins should be taut and unwrinkled, and their stems fresh and green. Watch out for soft or sunken areas, slashes or black spots. Except for jalapenos, which often have shallow cracks at their stem ends, chilli peppers should be free of cracks. Dried chilli peppers should be glossy and unbroken (wrinkled is fine), not dusty or fragmented.

Store unwashed chilli peppers, wrapped in paper towels, in the refrigerator for up to three weeks. Do not store them in a plastic bag, because trapped moisture will hasten spoilage. Check the chillies frequently; immediately use any that have developed soft spots. If you've bought more than you can use you can hang them to dry and use them in their dried form.

Store dried chilli peppers in an airtight container at room temperature for up to four months. If you are keeping them longer, place them in the refrigerator.

Exercise caution when handling chilli peppers. If the capsaicin contained in their inner flesh and seeds comes into contact with your skin or eyes, you will experience a very painful burning sensation. It's a good idea to wear thin rubber gloves when preparing chilies; if you don't wear gloves, be sure to wash your hands thoroughly with soap afterwards.

Wash the chillies just before using them. Next, cut them open and remove the seeds and ribs, if desired: This procedure tempers the chilies' pungency (soaking the peppers in cold salted water for an hour will further diminish their hotness).

To add the mildest chilli flavour to food, cut a few slits in a whole chilli pepper, impale it on a cocktail stick or skewer, then add it to food that is already cooking. When the dish is done, remove and discard the hot pepper.

With chilli peppers, you will find that even those of the same type vary in hotness. Consequently, you may need to use a different amount each time you prepare a favourite recipe. Sample a bit of the pepper before deciding how much to use in a particular dish. It's a good idea to add chillies a small amount at a time, until the food reaches the degree of hotness you desire.