BASIL
Basil actually includes several members of one Ocimum genus, and is related in part to peppermint. It was originally discovered in Africa and brought to us via India. Many Ocimum species are edible, although the most used one is Ocimum basilicum - the standard fragrant basil that is one of the most popular herbs in the world. Basil is known as l'herbe royale. It's name is derived from the Greek word basilikohn, which means royal (the same reason for calling some Church buildings basilicas). In ancient times, basil was believed to be a good medicine against venomous bites, although it is of course not really true. However, from nutritional point of view, basil is a very good guy. It is a good source of vitamin K, as well as iron, calcium, and vitamin A (prevents cholesterol oxidation). Basil also contains flavonoids (orientin and vicenin) that protect our DNA against radiation damage and oxidation. The flavorful oils in basil are also very good anti-bacterial compounds (eugenol, estragole, and others). Some basil oils have been shown to actually restrict the growth of antibiotic-resistant bacteria! Eugenol, the clove-smelling oil, can also block the activity of an enzyme (COX) that promotes inflammation. This same enzyme is the target of the common NSAID drugs, although basil has the advantage of not giving side-effects, e.g. ulcers. Inhibition of COX is also considered to be a powerful prevention of colorectal cancer, one of the most common and deadly cancers in our western civilization.
Basil has been cultivated to acquire other scents and flavors, e.g. that of lemon or anise, or thyme. Some basils may carry a stronger scent of cloves (like the classical Genovese basil) or a taste of tarragon or flowers. The exotic Thai basil tastes more like anise, and the Indian holy basil reminds a little of the Genovese clove-like quality.
If you buy fresh basil, you can store the picked leaves in refrigerator, however the best thing is to pick them just before use. When buying basil, make sure you find the one with nice green leaves without any strange spots. You can also grow your own basil if you want! Then, there is the dried basil, but it doesn't have that fresh tingling flavor at all. Also, if it has been sitting on a shelf of the grocery store for several months, it has lost even more of its flavor.
As any other plant, basil can acquire part of its taste from the soil in which it is grown. The different varieties of taste are also spread somewhat unevenly among the different leaves. For example, older leaves taste less and the younger smaller leaves taste much more. Also, the further away from the stalk you come, the more clove-like and tarragon-like the basil leaf will taste. The leaf part that is closer to the stalk tastes more flowery.
Basil is used as a main ingredient in pesto (and of course, the special pesto genovese), which also contains pine nuts, olive or sunflower oil, and parmesan cheese. Remember that basil is usually added at the end of cooking for the optimal taste experience. The reason is that it contains lots of volatile oils that will simply evaporate from the dish if cooked for too long. Try to balance the flavor infusion and evaporation then! Basil is commonly combined with dishes that contain tomatoes, but can also be used along other herbs, e.g. oregano. Basil can also be used with fish or meat, as a garnish or as a marinade ingredient. In short, basil enhances almost anything, and its healthy properties make it a desirable herb to use in cooking.