Chillies are native to South America however are now cultivated in many countries, from the Indian subcontinent to all over Asia. There are five main species of chilli and hundreds of varieties. Chillies come in a variety of shapes, colours and heat levels (which is measured in Scoville units).
Chillies have become the 'must use' daily condiment in the diets of many. The flavour and heat of chillies is associated with Indian, African, Asian and Mexican cooking. In cooking, if using oils and fats this will increase the heat of chillies. If you are unsure of the heat of the chilli always use less as you can add more later.