The burning sensation of chili is caused by the presence of capsaicin in it. The word 'capsaicin' means 'bite', thus denoting its fiery nature. The cream white seeds contain higher levels of capsaicin than the skin, thus the seeds are hotter to taste.

Capsaicin is produced in the chili fruit as a means of protection from mammals. In some Asian and African countries, the small hot chilies are also named bird's pod as they offer a delicious meal to birds. When consumed, capsaicin acts immediately on the pain receptors of the mouth and throat to produce the burning sensation.

Birds do not have these pain receptors to capsaicin to cause them pain. Thus, chilies, no matter how hot they can be, offer a fruitful meal to birds. In fact, birds help in the propagation of chilies.

Capsaicin can survive the process of heating and storage, thus retaining its characteristic fiery taste throughout cooking. These handy advantages also explain why it is so popularly used in culinary. It can be used to create wide varieties of recipes, offering endless choices to different demands from diners.

The degree of hotness, or the comparative capsaicin level, can be measured on the Scoville Scale. Each Scoville Unit measures part per million of capsaicin in a chilli.

So the only chili which is feared-not is the bell pepper, as it have zero capsaicin in it. The most feared, the hottest chili in the Guinness Book of Records is the naga jolokia from Bangladesh and Assam, India. Try it if you dare the devil!